Method, apparatus and system for managing bearers in a wireless communication system

ABSTRACT

Embodiments of the present disclosure describe methods, apparatuses, and systems for managing bearers in a wireless communication system. In some embodiments, an apparatus, to be employed by a user equipment (UE), may comprise a communication module to: communicate with a core network on a first bearer through a master evolved Node B (MeNB); receive, from the MeNB, a first message of reconfiguring a radio resource control (RRC) connection to establish a second bearer between the UE and the core network and through a secondary eNB (SeNB); synchronize, in response to the message, with the SeNB in order to establish the second bearer; and communicate with the core network on the second bearer through the SeNB, and continue communicating with the core network on the first bearer through the MeNB.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/753,914, filed Jan. 17, 2013, the entire disclosureof which is hereby incorporated by reference.

FIELD

Embodiments of the present disclosure generally relate to the field ofwireless communication systems, and more particularly, to bearermanagement in the wireless communication systems.

BACKGROUND

With explosion of mobile broadband data, advent of a small cell, alsoknown as a pico cell, may help to increase service coverage and/ormobile network capacities. The small cell may provide radio coveragefrom several meters to several kilometers. However, coexistence of macrocells and small cells in the network and frequent handovers between themacro cell and the small cell when a user equipment (UE) moves into orout of the small cell, may create a big challenge to current wirelessstandard technologies, such as 3rd Generation Partnership Project (3GPP)Long Term Evolution (LTE) project.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example and not by wayof limitation in the figures of the accompanying drawings.

FIG. 1 illustrates an embodiment of a wireless communication networkhaving coverage from a number of macro cells and small cells.

FIG. 2 illustrates an embodiment of a wireless communication system thatmay operate in compliance with the 3GPP LTE project along with anyamendments, updates and/or revisions.

FIG. 3 illustrates an embodiment of a signalling procedure for thewireless communication system to add a new bearer through a secondaryevolved Node B (SeNB) of the wireless communication system.

FIG. 4 illustrates an embodiment of a method for a user equipment (UE)of the wireless communication system to add the new bearer.

FIG. 5 illustrates an embodiment of a method for a master evolved Node B(MeNB) of the wireless communication system to add the new bearer.

FIG. 6 illustrates an embodiment of a signalling procedure to switch abearer from the MeNB to the SeNB of the wireless communication system,based on a S1 approach.

FIG. 7 illustrates an embodiment of a signalling procedure to switch thebearer from the MeNB to the SeNB of the wireless communication system,based on an X2 approach.

FIG. 8 illustrates an embodiment of a method for the UE of the wirelesscommunication system to switch the bearer from the MeNB to the SeNB.

FIG. 9 illustrates an embodiment of a method for the MeNB of thewireless communication system to switch the bearer from the MeNB to theSeNB, based on the S1 approach.

FIG. 10 illustrates an embodiment of a method for the MeNB of thewireless communication system to switch the bearer from the MeNB to theSeNB, based on the X2 approach.

FIG. 11 illustrates an embodiment of a method for the SeNB of thewireless communication system to switch the bearer from the MeNB to theSeNB based on the S1 approach.

FIG. 12 illustrates an embodiment of a method for the SeNB of thewireless communication system to switch the bearer from the MeNB to theSeNB based on the X2 approach.

FIG. 13 illustrates an embodiment of a signalling procedure for thewireless communication system to switch a bearer from the SeNB to theMeNB, based on the S1 approach.

FIG. 14 illustrates an embodiment of a signalling procedure for thewireless communication system to switch the bearer from the SeNB to theMeNB, based on the X2 approach.

FIG. 15 illustrates an embodiment of a method for the UE of the wirelesscommunication system to switch the bearer from the SeNB to the MeNB.

FIG. 16 illustrates an embodiment of a method for the MeNB of thewireless communication system to switch the bearer from the SeNB to theMeNB, based on the S1 approach.

FIG. 17 illustrates an embodiment of a method for the MeNB of thewireless communication system to switch the bearer from the SeNB to theMeNB, based on the X2 approach.

FIG. 18 illustrates an embodiment of a method for the SeNB of thewireless communication system to switch the bearer from the SeNB to theMeNB, based on the S1 approach.

FIG. 19 illustrates an embodiment of a method for the SeNB of thewireless communication system to switch the bearer from the SeNB to theMeNB, based on the X2 approach.

FIG. 20 illustrates an embodiment of a signalling procedure for thewireless communication system to switch a bearer from a source SeNB to atarget SeNB, based on the S1 approach.

FIG. 21 illustrates an embodiment of a signalling procedure for thewireless communication system to switch the bearer from the source SeNBto the target SeNB, based on the X2 approach.

FIG. 22 illustrates an embodiment of a method for the UE of the wirelesscommunication system to switch the bearer from the source SeNB to thetarget SeNB.

FIG. 23 illustrates an embodiment of a method for the MeNB of thewireless communication system to switch the bearer from the source SeNBto the target SeNB, based on the S1 approach.

FIG. 24 illustrates an embodiment of the method for the MeNB of thewireless communication system to switch the bearer from the source SeNBto the target SeNB, based on the X2 approach.

FIG. 25 illustrates an embodiment of a method for the source SeNB of thewireless communication system to switch the bearer from the source SeNBto the target SeNB, based on the S1 approach.

FIG. 26 illustrates an embodiment of a method for the source SeNB of thewireless communication system to switch the bearer from the source SeNBto the target SeNB, based on the X2 approach.

FIG. 27 illustrates an embodiment of a method for the target SeNB of thewireless communication system to switch the bearer from the source SeNBto the target SeNB, based on the S1 approach.

FIG. 28 illustrates an embodiment of a method for the target SeNB of thewireless communication system to switch the bearer from the source SeNBto the target SeNB, based on the X2 approach.

FIG. 29 illustrates an embodiment of an example system.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, wherein like numeralsdesignate like parts throughout, and in which is shown by way ofillustration embodiments in which the subject matter of the presentdisclosure may be practiced. It is to be understood that otherembodiments may be utilized and structural or logical changes may bemade without departing from the scope of the present disclosure.Therefore, the following detailed description is not to be taken in alimiting sense, and the scope of embodiments is defined by the appendedclaims and their equivalents.

Various operations are described as multiple discrete operations inturn, in a manner that is most helpful in understanding the claimedsubject matter. However, the order of description should not beconstrued as to imply that these operations are necessarily orderdependent. In particular, these operations may not be performed in theorder of presentation. Operations described may be performed in adifferent order than the described embodiment. Various additionaloperations may be performed and/or described operations may be omittedin additional embodiments.

For the purposes of the present disclosure, the phrase “A/B” means “A orB”. The phrase “A and/or B” means “(A), (B), or (A and B)”. The phrase“at least one of A, B and C” means “(A), (B), (C), (A and B), (A and C),(B and C) or (A, B and C)”. The phrase “(A) B” means “(B) or (A B)”,that is, A is optional.

The description may use the phrases “in an embodiment,” or “inembodiments,” which may each refer to one or more of the same ordifferent embodiments. Furthermore, the terms “comprising,” “including,”“having,” and the like, as used with respect to embodiments of thepresent disclosure, are synonymous.

As used herein, the term “module” may refer to, be part of, or includean Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group) and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablecomponents that provide the described functionality.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a wide variety of alternate and/or equivalent implementations maybe substituted for the specific embodiments shown and described, withoutdeparting from the scope of the embodiments of the present disclosure.This application is intended to cover any adaptations or variations ofthe embodiments discussed herein. Therefore, it is manifestly intendedthat the embodiments of the present disclosure be limited only by theclaims and the equivalents thereof.

FIG. 1 illustrates an embodiment of a wireless communication network 100that may operate in compliance with Long Term Evolution (LTE) standardsof 3rd Generation Partnership Project (3GPP). The wireless communicationnetwork 100 may have coverage from a number of macro cells and smallcells. As illustrated in the FIG. 1, a hexagon cell may represent amacro cell, and an elliptical cell may represent a small cell. Invarious embodiments, the small cell may be placed inside of the macrocells or on a border of the macro cell. The small cell, also known asthe pico cell, may provide radio coverage from several meters to severalkilometers. On the contrary, in some cases, the macro cell may haveradio coverage of a few tens of kilometers.

FIG. 2 illustrates an embodiment of a wireless communication system 200that may operate in compliance with the 3GPP LTE project along with anyamendments, updates, and/or revisions (e.g., LTE-Advanced (LTE-A),etc.). The wireless communication system 200 may comprise a userequipment (UE) 201, a master evolved Node B (MeNB) 202 for the macrocell, a secondary evolved Node B (SeNB) 203 for the small cell, and acore network system 204, wherein the UE 201 may be dual-connected withthe MeNB 202 and the SeNB 203 according to a S1 approach or an X2approach. Other embodiments may implement other modifications andvariations on the MeNB 202 and/or the SeNB 203. For example, the MeNB202 may be designed for another small cell. Similarly, the SeNB 203 maybe designed for another macro cell.

The UE 201 may be embodied as, without limitation, a smart phone, acellular telephone, a tablet, a consumer electronic device, a laptopcomputer, a notebook computer, a mobile computing system, aprocessor-based system, and/or any other mobile communication deviceconfigured to communicate with the core network system 204 via the MeNB202 and/or the SeNB 203. The core network system 204 may be embodied asan evolved packet core (EPC) which may comprise, a mobility managemententity (MME) 214, a serving gateway (S-GW) 224, a packet data networkgateway (PDN GW) 234, and others.

Under the dual connectivity, bearers carrying data flows between the UE201 and the core network system 204 may split between the MeNB 202 andthe SeNB 203, for example, the bearers through the MeNB 202 and thebearers through the SeNB 203. Examples for the bearers may includeevolved packet system (EPS) bearers. In some embodiments, the EPS bearermay comprise a bearer between the UE 201 and the MeNB 202 such as a dataradio bearer (DRB), a bearer between the MeNB 202 and the S-GW 224 suchas a S1 bearer, a bearer between S-GW 224 and PDN GW 234 such as S5/S8bearer, and/or others. In some embodiments, an Evolved UniversalTerrestrial Radio Access Network (EUTRAN) radio access bearer (E-RAB)between the UE 201 and the S-GW 224 may identify the concatenation ofthe corresponding DRB and the S1 bearer.

According to the S1 approach, the MeNB 202 and the SeNB 203 may connectdirectly with the core network system 204 via a S1 interface and thebearers for different eNBs may be split at the core network system 204.According to the X2 approach, the SeNB 203 may indirectly connect withthe core network system 204, namely, through an X2 interface of the MeNB202. Therefore, the bearers may be split at the MeNB 202.

As illustrate in FIG. 2, in various embodiments, the UE 201 may includea communication module 211, and/or others. The communication module 211may receive or transmit a signalling/packet from/to the MeNB 202 and/orSeNB 203 in the wireless communication system 200. In some embodiments,the communication module 211 may further generate, process and/orcontrol the signalling/packet and/or other communications from/to the UE201. Details about functionalities of the communication module 211 maybe provided in the following descriptions. The communication module 211may include several layer implementations, such as a physical layermodule 2110, a L2 layer module 2111, a radio resource communication(RRC) layer module 2112, a non-access stratum (NAS) layer module 2113,and/or others.

In various embodiments, the MeNB 202 may include a communication module212, and/or others. The communication module 212 may receive or transmita signalling/packet from/to the UE 201, SeNB 203 and/or core networksystem 204 in the wireless communication system 200. In someembodiments, the communication module 212 may further generate, processand/or control the signalling/packet and/or other communications from/tothe MeNB 202. Details about functionalities of the communication module212 may be provided in the following descriptions. The communicationmodule 212 may include several layer implementations, such as a physicallayer module 2120, a L2 layer module 2121, a radio resourcecommunication (RRC) layer module 2122, a non-access stratum (NAS) layermodule 2123, and/or others.

In various embodiments, the SeNB 203 may include a communication module213, and/or others. The communication module 213 may receive or transmita signalling/packet from/to the UE 201, MeNB 202 and/or core networksystem 204 of the wireless communication system 200. In someembodiments, the communication module 213 may further generate, processand/or control the signalling/packet and/or other communications from/tothe SeNB 203. Details about functionalities of the communication module213 may be provided in the following descriptions. The communicationmodule 213 may include several layer implementations, such as a physicallayer module 2130, a L2 layer module 2131, a radio resourcecommunication (RRC) layer module 2132, a non-access stratum (NAS) layermodule 2133, and/or others.

FIG. 3 illustrates an embodiment of a signalling procedure for thewireless communication system 200 to add SeNB resources by adding a newbearer through the SeNB 203, such as a new EPS bearer between the UE 201and the core network system 204 and through the SeNB 203 for the smallcell. In various embodiments, the UE 201 may communicate with the corenetwork system 204 via a default bearer (e.g., a default EPS bearer)established through the MeNB 202 for the macro cell. In order to createthe new bearer through the SeNB 203, during the signalling procedure asdepicted in FIG. 3, the UE 201 may transmit a request to the MeNB 202 torequest allocation of a new bear resource for a traffic flow aggregation(signalling 301). In some embodiments, the UE 201 may move into thesmall cell which may trigger a determination of requesting theallocation of the new bearer resource.

The request may be embodied as, without limitation, an uplinkinformation transfer and a non-access stratum (NAS) bearer resourceallocation request, and may include a specific quality of service (QoS)demand, a guaranteed bit rate (GBR) requirement for a new traffic flowaggregate and/or other information related to a dedicated EPS bearercontext.

In some embodiments, the MeNB 202 may transport the request to the MME214 (signalling 302), which may then transmit a bearer resource commandto the S-GW 224 in response to a determination that the request isacceptable (signalling 303). However, in response to a determinationthat the request is not acceptable, the MME 214 may reject the requestby transmitting a rejection message. In some embodiments, the bearerresource command may be further forwarded to the PDN GW 234 (signalling304). In response to a determination that the bearer resource commandmay be acceptable, the PDN GW 234 may transmit a create bearer requestto the S-GW 224 (signalling 305), which may then forward the request tothe MME 214 (signalling 306). However, in response to a determinationthat the bearer resource command may be unacceptable, the PDN GW 234 maytransmit a rejection message to the S-GW 224 and then indirectly to theMME 214.

Upon receiving the create bearer request, the MME 214 may initiate adedicated bearer context activation procedure by transmitting a requestto setup the new bearer with dedicated bearer context (signalling 307).The request may be embodied as E-RAB setup request and NAS activatededicated EPS bearer context request.

Upon receipt of the request from MME 214, the MeNB 202 may select asmall cell or a SeNB through which the new bearer can be established. Insome embodiments, the MeNB 202 may select the small cell or the SeNBbased on a UE measurement report related to a UE communication quality.The MeNB 202 may further transmit a request of adding the small cell orthe SeNB by establishing the new bearer through the selected SeNB 203(signalling 308). The request may be embodied as a SeNB addition requestor a small cell addition request (not illustrated in FIG. 3) and mayinclude, without limitation, information element (IE) such as cause forthe the SeNB addition or the small cell addition, a list of E-RABs to besetup, characteristics of the new bearer (such as E-RAB parameters,transport network layer (TNL) address information, and/or others), UEsecurity capabilities for S1 approach, security context for S1 approach,and/or others.

In response to a determination that the request from MeNB 202 isacceptable, such as when the QoS requirement of the new bearer can besatisfied, the SeNB 203 may transmit a message, e.g., a SeNB additionrequest acknowledgement (ACK) or a small cell addition request ACK (notillustrated in FIG. 3), to the MeNB 202 (signalling 309). The SeNBaddition request ACK or the small cell addition request ACK may include,without limitation, a list of admitted E-RABs including TNL addressinformation for the respective E-RAB, a list of not admitted E-RABs, atransparent container to be sent to the UE for the small cell additionor the SeNB addition, and/or others. The transparent container mayinclude, without limitation, a new cell-radio network temporaryidentifier (C-RNTI) for identifying the UE 201 by the SeNB 203,secondary eNB security algorithm identifiers for selected securityalgorithms, a dedicated random access channel (RACH) preamble, accessparameters, system information blocks (SIBs) parameters, and/or others.However, in response to a determination that the request from MeNB 202is unacceptable, the SeNB 203 may transmit a rejection message to theMeNB 202.

Upon receipt of the acknowledgement message, the MeNB 202 may transmit arequest to the UE 201 to request reconfiguring a radio resource control(RRC) connection to establish the new bearer through the SeNB 203 forthe small cell (signalling 310). The request may be embodied as, withoutlimitation, a RRC connection reconfiguration (i.e.,RRCconnectionreconfiguration) and NAS activate dedicated EPS bearercontext request, and may include information such as C-RNTI, securityalgorithm identifiers, dedicated RACH preamble for the small cell,and/or others. In some embodiments, the C-RNTI may not be needed if theUE 201 is allocated with the same C-RNTI in the macro cell and the smallcell, and the security algorithm identifiers may not be needed if X2approach is used.

Based on the information in the RRCconnectionreconfiguration and NASactivate dedicated EPS bearer request, the UE 201 may perform uplink anddownlink synchronization with the SeNB 203 in order to reconfigure theRRC connection to establish the new bearer with the dedicated EPS bearercontext (signalling 311). For example, the UE 201 may perform thesynchronization to the SeNB 203 and access the small cell via RACH,following a contention-free or contention-based procedure depending onwhether a dedicated preamble was indicated or not. In some embodiments,the UE 201 may meanwhile keep the default bearer through the MeNB 202 aswell as a signalling radio bearer (SRB) through the MeNB 202. In thisway, the UE 201 may be dual-connected with the MeNB 202 and the SeNB203. Then, the UE 201 may transmit a RRC connection reconfigurationcomplete message (i.e., RRCconnectionreconfigurationcomplete) to theMeNB 202 (signalling 312), and the MeNB 202 may further transmit a SeNBaddition complete message or a small cell addition complete message (notillustrated in FIG. 3) to the SeNB 203 (Signalling 313). Alternatively,the UE 201 may transmit the RRCconnectionreconfigurationcomplete messageto the MeNB 202 as well as the SeNB 203. The UE 201 may be ready tocommunicate with the new bearer through the SeNB 203, and SeNB 203 maybuffer packet data received from the UE 201 until a connection with theS-GW 224 is established.

In some embodiments, the MeNB 202 may then transmit an E-RAB setupresponse to the E-RAB setup request from MME 214 (signalling 314). TheE-RAB setup response may be embodied as, without limitation, a S1application protocol (S1AP) E-RAB setup response for the S1 approach oran X2 application protocol (X2AP) E-RAB setup response for the X2approach. The E-RAB setup response may inform the MME 214 that the newbearer was created and was re-directed to the SeNB 203 and may includean indicator that the E-RAB may be handled by the SeNB, an IP addressesof the SeNB, and/or others.

The UE 201 may further transmit a message informing the MeNB 202 thatthe dedicated bearer context is accepted, such as a NAS activatededicated EPS bearer context accept message to the MeNB 202 (signalling315). This message may be transmitted in response to the above-statedNAS activate dedicated EPS bearer context request. The MeNB 202 mayfurther forward the message to the MME 214 (signalling 316).

Upon receipt of the E-RAB setup response and the NAS activate dedicatedEPS bearer context accept message, the MME 214 may transmit a createbearer response to the S-GW 224 (signalling 317), which may be theresponse to the above-stated create bearer request from the S-GW 224. Inthis way, the connection between the SeNB 203 and the S-GW 224 may beestablished, resulting in the establishment of the new bearer betweenthe UE 201 and the S-GW 224.

Other embodiments may implement other modifications and variations to onthe signalling procedure as depicted in FIG. 3. For example, althoughFIG. 3 illustrates the signalling procedure of adding the new cell asinitiated by the UE 201, it should be understood that a similarprocedure as initiated by the network 204 can accomplish the similarresult.

FIG. 4 illustrates an embodiment of a method for the UE 201 to add theSeNB resources by adding the new bearer through the SeNB 203 for thesmall cell. In block 401, the communication module 211 or other deviceof the UE 201 may communicate with the core network system 204 on thedefault bearer, such as the default EPS bearer through the MeNB 202. Inblock 402, the communication module 211 or other device may determinethat the new bearer is needed for the traffic flow aggregation. In someembodiments, the UE 201 may move into the small cell which may triggerthe determination for the new bearer through the small cell. In block403, the communication module 211 (e.g., NAS layer module 2113) or otherdevice may transmit the NAS bearer resource allocation request to theMeNB 202. In block 404, the communication module 211 (e.g., RRC layermodule 2112) or other device may receive, from the MeNB 202, the requestof adding the new bearer through the SeNB 203 for the small cell. Therequest may be embodied as the RRCconnectionreconfiguration and NASactivate dedicated EPS bearer context request, and may includeinformation such as C-RNTI, security algorithm identifiers, dedicatedRACH preamble for the small cell, and/or others. In some embodiments,the C-RNTI may not be needed if the UE 201 is allocated with the sameC-RNTI in the macro cell and the small cell, and the security algorithmidentifiers may not be needed if X2 approach is used.

In block 405, the communication module 211 (e.g., the RRC layer 2112) orother device may synchronize with the SeNB 203 to reconfigure the RRCconnection for the new bearer establishment. In some embodiments, the UE201 may perform uplink and downlink synchronization based on theinformation contained in the request. In some embodiments, the UE 201may meanwhile keep the default bearer through the MeNB 202 as well as asignalling radio bearer (SRB) through the MeNB 202. Thus, the UE 201 maybe dual-connected with the MeNB 202 and the SeNB 203.

In block 406, the communication module 211 (e.g., the RRC layer 2112) orother device may transmit the RRCconnectionreconfigurationcompletemessage to the MeNB 202. In some embodiments, the message may be furthertransmitted to the SeNB 203. In block 407, the communication module 211(e.g., the NAS layer 2113) or other device may transmit the NAS activatededicated EPS bearer context accept message to the MeNB 202.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 4. For example, although FIG. 4illustrates the method of adding the new bearer as initiated by the UE201, it should be understood that a similar procedure as initiated bythe network 204 can accomplish the similar result.

FIG. 5 illustrates an embodiment of a method for the MeNB 202 of thewireless communication network 200 to add the SeNB resources by addingthe new bearer through the SeNB 203 for the small cell. In block 501,the communication module 212 or other device of the MeNB 202 maycommunicate with the UE 201 on the default bearer through the macrocell, such as the EPS bearer. In block 502, the communication module 212(e.g., NAS layer 2123) or other device may receive the NAS bearerresource allocation request from the UE 201. In block 503, thecommunication module 212 (e.g., NAS layer 2123) or other device mayforward the NAS bearer resource allocation request to the MME 214. Inblock 504, the communication module 212 (e.g., NAS layer 2123) or otherdevice may receive the E-RAB setup request and NAS activate dedicatedEPS bearer context request from the MME 214, as a part of the dedicatedbearer context activation procedure. In block 505, the communicationmodule 212 or other device may select the small cell or the SeNB throughwhich the new bearer can be established. In some embodiments, the MeNB202 may select the small cell or the SeNB based on the UE measurementreport related to the UE communication quality.

In block 506, the communication module 212 or other device may furthertransmit to the SeNB 203 the request of adding the new bearer. Therequest may be embodied as the SeNB addition request or the Small Celladdition request and may include, without limitation, informationelement (IE) such as cause for the SeNB addition, a list of E-RABs to besetup, characteristics of the new bearer, UE security capabilities forS1 approach, security context for S1 approach, and/or others.

In block 507, the communication module 212 or other device may receive,from the SeNB 203, the acknowledgement message such as the SeNB additionrequest ACK or the small cell addition request ACK (not illustrated inFIG. 5), if the SeNB 203 determines that the SeNB addition request orthe small cell addition request is acceptable. The SeNB addition requestACK the small cell addition request ACK may include, without limitation,a list of admitted E-RABs including TNL address information for therespective E-RAB, a list of not admitted E-RABs, a transparent containerto be sent to the UE for SeNB addition or small cell addition, and/orothers. The transparent container may include, without limitation, a newcell-radio network temporary identifier (C-RNTI) for identifying the UE201 by the SeNB 203, secondary eNB security algorithm identifiers forselected security algorithms, a dedicated random access channel (RACH)preamble, access parameters, system information blocks (SIBs)parameters, and/or others. However, the communication module 212 orother device may receive the rejection message, if the SeNB 203determines that the SeNB addition request or the small cell additionrequest is unacceptable.

In block 508, the communication module 212 (e.g., RRC layer 2122) orother device may transmit the RRCconnectionreconfiguration and NASactivate dedicated EPS bearer context request to the UE 201 to requestreconfiguring the RRC connection to establish the new bearer through theSeNB 203. In some embodiments, the RRCconnectionreconfiguration and NASactivate dedicated EPS bearer context request may include informationsuch as C-RNTI, security algorithm identifiers, dedicated RACH preamblefor the small cell, and/or others. In some embodiments, the C-RNTI maynot be needed if the UE 201 is allocated with the same C-RNTI in themacro cell and the small cell, and the security algorithm identifiersmay not be needed if X2 approach is used.

In some embodiments, the communication module 212 (e.g., RRC layer 2122)or other device may receive the RRC connection reconfiguration completemessage from the UE 201 in block 509, and may transmit to MME 214 anE-RAB setup response to the E-RAB setup request in block 510. The E-RABsetup response may be embodied as, without limitation, a S1 applicationprotocol (S1AP) E-RAB setup response for the S1 approach or an X2application protocol (X2AP) E-RAB setup response for the X2 approach.The E-RAB setup response may inform the MME 214 that the new bearer wascreated and was re-directed to the SeNB 203.

In block 511, the communication module 212 (e.g., NAS layer 2123) orother device may further receive the NAS activate dedicated EPS bearercontext accept message from the UE 201, which may be transmitted inresponse to the above-stated NAS activate dedicated EPS bearer contextrequest. The communication module 212 (e.g., NAS layer 2123) or otherdevice may further forwarded the message to the MME 214.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 5. For example, although FIG. 5illustrates the method of adding the new bearer as initiated by the UE201, it should be understood that a similar procedure as initiated bythe network 204 can accomplish the similar result.

FIG. 6 illustrates an embodiment of a signalling procedure to adding theSeNB resources by switching a bearer from the MeNB 202 to the SeNB 203of the wireless communication system 200, based on the S1 approach.

As illustrated in FIG. 6, based on the S1 approach, the UE 201 maycommunication with the core network system 204 over a DRB of an EPSbearer established through the MeNB 202 for the macro cell. The MeNB 202may transmit a message related to measurement control to the UE 201(signalling 601). In some embodiments, the message may configure the UEmeasurement procedures according to area restriction information.Measurements provided by the MeNB 202 may assist the functioncontrolling the UE's connection mobility. In response to the message,the UE 201 may perform the measurement procedures and transmit ameasurement report to the MeNB 202 (signalling 602). Based on themeasurement report, the MeNB 202 may make a decision of switching theDRB from the macro cell to the small cell. This may happen under certaincircumstances, such as when the UE 201 moving into the coverage of thesmall cell. As illustrated in FIG. 6, the decision may be called as acarrier aggregation (CA) decision. On the other hand, although not beingillustrated in FIG. 6, it should be understood that the MeNB 202 maymake a decision of not adding the small cell, for example, when themeasurement report indicates that the radio quality in the small cell isnot good enough.

The MeNB 202 may send a request of adding the small cell to the SeNB 203for the small cell (signalling 603). The request may be embodied as aSeNB addition request or a small cell addition request (not illustratedin FIG. 6), and may include, without limitation, information element(IE) such as cause for the SeNB addition or the small cell addition, alist of E-RABs to be setup, characteristics of the DRB (such as DRBparameters, TNL address information and/or others), UE securitycapabilities for S1 approach, security context for S1 approach, and/orothers.

Then, the SeNB 203 may perform an admission control to determine whetherthe request is acceptable or not. In response to a determination thatthe request is acceptable, the SeNB 203 may send a message to the MeNB202, such as a SeNB addition request ACK or a small cell additionrequest ACK (not illustrated in FIG. 6) (signalling 604). The SeNBaddition request ACK or the SeNB addition request or the small celladdition request ACK may include, without limitation, a list of admittedE-RABs including TNL address information for the respective E-RAB, alist of not admitted E-RABs, a transparent container to be sent to theUE for the SeNB addition or the small cell addition, and/or others. Thetransparent container may include, without limitation, a new C-RNTI foridentifying the UE 201 by the SeNB 203, secondary eNB security algorithmidentifiers for selected security algorithms, a dedicated random accesschannel (RACH) preamble, access parameters, system information blocks(SIBs) parameters, and/or others.

Upon receipt of the acknowledgment message, the MeNB 202 may transmit tothe UE 201 a message of reconfiguring the RRC connection to switch theDRB from the MeNB 202 to the SeNB 203 (signalling 605). The message maybe embodied as, without limitation, a RRCconnectionreconfigurationmessage, and may include information related to the small cell or theSeNB 203 such as the new C-RNTI, SeNB security algorithm identifiers andoptionally dedicated RACH preamble, SeNB system information blocks(SIBs), and/or others.

In some embodiments, the MeNB 202 may start to deliver buffered and intransit packet data to the SeNB 203. Before forwarding the packet data,the MeNB 202 may transfer serial number (SN) status to the SeNB 203(signalling 606). In some embodiments, the MeNB 202 may convey uplinkPDCP (packet data convergence protocol) SN receiver status and/ordownlink PDCP SN transmitter status of E-RABs for which PDCP statuspreservation applies. The SeNB 203 may buffer the packet data receivedfrom the MeNB 202, such as a memory or a data storage of the SeNB 203.

Based on the information in the RRCconnectionreconfiguration message,the UE 201 may perform uplink and/or downlink synchronization with theSeNB 203 in order to reconfigure the RRC connection to switch the DRBfrom the macro cell to the small cell. For example, the UE 201 mayperform the synchronization to the SeNB 203 and access the small cellvia RACH, following a contention-free or contention-based proceduredepending on whether a dedicated preamble was indicated or not. In someembodiments that the UE 201 may communication with the MeNB 202 on morethan one DRBs, after switching the DRB from the macro cell to the smallcell, the UE 201 may still keep remaining DRB bearer(s) (i.e.,unswitched DRB(s)) with the MeNB 202 as well as a SRB with the MeNB 202.In this way, the UE 201 may be dual-connected with the MeNB 202 and theSeNB 203.

After synchronizing with the SeNB 203 and being able to access the smallcell, the UE 201 may transmit a RRCconnectionreconfigurationcompletemessage to the MeNB 202 to inform that the RRC connectionreconfiguration has been completed and the small cell has beensuccessfully added (signalling 607). The MeNB 202 may then transmit asmall cell addition complete message to the SeNB 203 (Signalling 608).Alternatively, the UE 201 may transmit theRRCconnectionreconfigurationcomplete message to the MeNB 202 as well asthe SeNB 203.

In some embodiments, after the UE 201 can access the small cell, it maytransmit an uplink packet to the SeNB 203 over the DRB through the smallcell, which may be transferred by the SeNB 203 to the core networksystem 204. The SeNB 203 may further transmit a path switch request tothe MME 214 to request switching a downlink path of the EPS bearer frombetween the MeNB 202 and the core network system 204 to between the SeNB203 and the core network system 204 (signalling 609), wherein the DRB ofthe EPS bearer has already been switched from the MeNB 202 to the SeNB203. The path switch request may include a list of the EPS bearer(s)whose DRB(s) have been switched. In some embodiments, the path switchrequest may further indicate to keep other bearer(s) unreleased, whereinthe other bearer(s) may include those not listed in the request, such asthe DRBs related to the MeNB 202 but not switched to the SeNB 203,and/or the SRBs related to the MeNB 202. In this way, the UE 201 maystill be connected to the MeNB 202 while communicating with the SeNB203. Alternatively, the MeNB 202 may send a separate request of keepingthe other bearer(s) unreleased to the MME 214.

Upon receipt of the path switch request, the MME 214 may transmit amodify bearer request to the S-GW 224 to request modifying the downlinkpath of the listed EPS bearer(s) to go through the SeNB 203 (signalling610). In response to the request, the S-GW 224 may switch the downlinkpath, so that the downlink packet data can be transmitted from the corenetwork system 204 to the UE 201 through the SeNB 203. In someembodiments, the S-GW 224 may further send an End Marker to the MeNB 202indicating an end of downlink packet data transmission on the old pathto the MeNB 202 (signalling 611). The MeNB 202 may send another EndMarker to the SeNB 203 indicating an end of data forwarding from theMeNB 202 to the SeNB 203 (signalling 612).

After the completion of the bearer modification, the S-GW 224 may sendwith a modify bearer response to the MME 214 (signalling 613), which maytrigger the MME 214 to transmit an acknowledgement message to the SeNB203, such as a path switch request ACK (signalling 614).

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 6. For example, more than one DRBs may beswitched from the MeNB 202 to the SeNB 203 in order to add the SeNBresources. For another example, the path switch request may betransmitted by the MeNB 202, rather than by the SeNB 203 to the MME 214.

FIG. 7 illustrates an embodiment of a signalling procedure to add theSeNB resources by switching the bearer from the MeNB 202 to the SeNB 203of the wireless communication system 200, based on the X2 approach. Insome embodiments, the signalling procedure of FIG. 7 may be similar asthat of FIG. 6. However, due to the X2 approach, after the completion ofRRC connection reconfiguration to switch the DRB(s) of the EPS bearer(s)from the MeNB 202 to the SeNB 203 (signalling 708), the transmissions ofthe packet data over the EPS bearer(s) may have to go through the SeNB203 and then through the MeNB 202, namely, the UE 201 mayreceive/transmit the packet data from/to the SeNB 203, which may furthercommunicate the packet data from/to the core network system 204 throughthe MeNB 202. In this way, there may be no need to request the corenetwork system 204 to modify the downlink path of the EPS bearer(s) fromthe MeNB 202 to the SeNB 203.

FIG. 8 illustrates an embodiment of a method for the UE 201 of thewireless communication system 200 to adding the SeNB resources byswitching the bearer from the MeNB 202 to the SeNB 203. In someembodiments, the UE 201 may communication with the core network system204 over the DRB of the EPS bearer established through the MeNB 202 forthe macro cell. In block 801, the communication module 211 or otherdevice of UE 201 may receive, from the MeNB 201, the message related tothe measurement control which may configure the UE measurementprocedures. Measurements provided by the MeNB 202 may assist thefunction controlling the UE's connection mobility. In response to themessage, in block 802, the communication module 211 or other device ofthe UE 201 may perform the measurement and transmit the measurementreport to the MeNB 202. Based on the measurement report, the MeNB 202may make the decision of adding the small cell by switching the DRB fromthe MeNB 202 to the SeNB 203. This may happen under certaincircumstances, such as when the UE 201 moving into the coverage of thesmall cell. However, it should be understood that the MeNB 202 may makea decision of not adding the small cell, for example, when themeasurement report indicates that the radio quality in the small cell isnot good enough.

In response to the decision of adding the small cell, in block 803, thecommunication module 211 (e.g., RRC layer 2112) or other device mayreceive a message of reconfiguring the RRC connection to add the smallcell by switching the DRB from the MeNB 202 to the SeNB 203. The messagemay be embodied as, without limitation, a RRCconnectionreconfigurationmessage, and may include information related to the small cell such asthe new C-RNTI, SeNB security algorithm identifiers and optionallydedicated RACH preamble, SeNB system information blocks (SIBs), and/orothers.

In block 804, based on the information in theRRCconnectionreconfiguration message, the communication module 211(e.g., RRC layer 2112) or other device may perform the uplink and/ordownlink synchronization with the SeNB 203 in order to reconfigure theRRC connection to switch the DRB from the MeNB 202 to the SeNB 203. Forexample, the communication module 211 may perform the synchronization tothe SeNB 203 and access the small cell via RACH, following acontention-free or contention-based procedure depending on whether adedicated preamble was indicated or not. In some embodiments that the UE201 may communication with the MeNB 202 on more than one DRBs, afterswitching the DRB from the macro cell to the small cell, the UE 201 maystill keep the remaining DRB bearer(s) (i.e., the unswitched DRB(s))with the MeNB 202 as well as the SRB with the MeNB 202. In this way, theUE 201 may be dual-connected with the MeNB 202 and the SeNB 203.

In block 805, after synchronizing with the SeNB 203 and being able toaccess the small cell, the communication module 211 (e.g., RRC layer2112) or other device may transmit theRRCconnectionreconfigurationcomplete message to the MeNB 202 and/or SeNB203 to inform that the RRC connection reconfiguration has been completedand the small cell has been successfully added. In block 806, thecommunication module 211 or other device may receive/transmit the packetdata from/to the SeNB 203.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 8. For example, more than one DRBs may beswitched from the MeNB 202 to the SeNB 203 in order to add the SeNBresources.

FIG. 9 illustrates an embodiment of a method for the MeNB 202 of thewireless communication system 200 to add the SeNB resources by switchingthe bearer from the MeNB 202 to the SeNB 203, based on the S1 approach.According to the S1 approach, in block 901, the communication module 212or other device of MeNB 202 may communicate the packet data between theUE 201 and the core network system 204 over the DRB of the EPS bearerestablished through the macro cell. In block 902, the communicationmodule 212 or other device may transmit the message related to themeasure control to the UE 201. In some embodiments, the message mayconfigure the UE measurement procedures according to area restrictioninformation. Measurements provided by the MeNB 202 may assist thefunction controlling the UE's connection mobility.

In block 903, the communication module 212 or other device may receivethe measurement report from the UE 201. In block 904, based on themeasurement report, the communication module 212 or other device maymake the decision of adding the SeNB resources by switching the DRB fromthe MeNB 202 to the SeNB 203. On the other hand, although not beingillustrated in FIG. 9, the communication module 212 or other device maymake the decision of not adding the small cell.

In response to the decision of adding the SeNB resources, thecommunication module 212 or other device may send to the SeNB 203 therequest of adding the SeNB resources by switching the DRB from the MeNB202 to the SeNB 203, in block 905. In some embodiments, the request maybe embodied as a SeNB addition request or a small cell addition request(not illustrated in FIG. 9), and may include, without limitation,information element (IE) such as cause for the SeNB addition or smallcell addition, the list of E-RABs to be setup, characteristics of theDRB, UE security capabilities for S1 approach, security context for S1approach, and/or others.

In block 906, the communication module 212 or other device may receive,from the UE 201, the acknowledgement message such as the SeNB additionrequest ACK or the small cell addition request ACK (not illustrated inFIG. 9). In some embodiments, the SeNB addition request ACK or the smallcell addition request ACK may include, without limitation, the list ofadmitted E-RABs (such as E-RAB parameters, TNL address information,and/or others), the list of not admitted E-RABs, a transparent containerto be sent to the UE for the SeNB addition or the small cell addition,and/or others. The transparent container may include, withoutlimitation, the new C-RNTI for identifying the UE 201 by the SeNB 203,SeNB security algorithm identifiers for selected security algorithms,the dedicated RACH preamble, access parameters, SIBs parameters, and/orothers.

Upon receipt of the acknowledgment message, in block 907, thecommunication module 212 (e.g., RRC layer 2122) or other device maytransmit to the UE 201 the message of reconfiguring the RRC connectionto add the SeNB resources by switching the DRB from the MeNB 202 to theSeNB 203. The message may be embodied as, without limitation, theRRCconnectionreconfiguration message, and may include informationrelated to the small cell or the SeNB 203 such as the new C-RNTI, SeNBsecurity algorithm identifiers and optionally dedicated RACH preamble,SeNB system information blocks (SIBs), and/or others. In someembodiments that the UE 201 may communication with the MeNB 202 on morethan one DRBs, after switching the DRB from the MeNB 202 to the SeNB203, the UE 201 may still keep the remaining DRB bearer (i.e., theunswitched DRB) with the MeNB 202 as well as the SRB with the MeNB 202.In this way, the UE 201 may be dual-connected with the MeNB 202 and theSeNB 203.

Then, the MeNB 202 may start to deliver the buffered and in transitpacket data to the SeNB 203. Before forwarding the packet data in block909, the communication module 212 or other device may transfer theserial number (SN) status to the SeNB 203 in block 908. In someembodiments, the MeNB 202 may convey uplink PDCP (packet dataconvergence protocol) SN receiver status and/or downlink PDCP SNtransmitter status of E-RABs for which PDCP status preservation applies.The SeNB 203 may buffer the packet data received from the MeNB 202, forexample, in the memory or the data storage of the SeNB 203.

After the UE 201 synchronizing with the SeNB 203 and being able toaccess the small cell, in block 910, the communication module 212 (e.g.,RRC layer 2122) or other device may receive, from the UE 201, theRRCconnectionreconfigurationcomplete message which may inform that theRRC connection reconfiguration has been completed and the SeNB resourceshas been successfully added. In some embodiments, the communicationmodule 212 or other device may then transmit the SeNB addition completemessage or small cell addition complete message (not illustrated in FIG.9) to the SeNB 203, in block 911. However, in other embodiments that theUE 201 transmits the RRCconnectionreconfigurationcomplete message to theMeNB 202 and the SeNB 203, the block 911 may be omitted.

In block 912, the communication module 212 or other device may send a S1or X2 message to the S-GW 224, in order to keep the bearer(s)unreleased, which bearer(s) are related to the MeNB 202 and haven't beenswitched to the SeNB 203. The bearer(s) may include DRB(s) and/orSRB(s). In this way, the UE 201 may still connect with the MeNB 202. Insome embodiments, the similar message may be conveyed to the S-GW 224 bythe SeNB 203. In such case, block 912 may be omitted.

In block 912, the communication module 212 or other device may receivefrom the core network system (e.g., S-GW 224), the end marker indicatingthe end of downlink packet data transmissions from the core networksystem to the MeNB 202 over the old path. In block 913, thecommunication module 212 or other device may transmit, to the SeNB 203,the end marker indicating the end of data forwarding from the MeNB 202to the SeNB 203.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 9. For example, the communication module212 or other device may further transmit, to the MME 214, the pathswitch request to request switching the downlink path of the EPS bearerfrom between the MeNB 202 and the core network system 204 to between theSeNB 203 and the core network system 204, wherein the DRB of the EPSbearer has already been switched from the MeNB 202 to the SeNB 203. Thepath switch request may include the list of the EPS bearer(s) whoseDRB(s) have been switched. In some embodiments, the path switch requestmay further indicate to keep other bearer(s) unreleased, wherein theother bearer(s) may include those not listed in the request, such as theDRBs related to the MeNB 202 but not switched to the SeNB 203, and/orthe SRBs related to the MeNB 202. In this way, the UE 201 may still beconnected to the MeNB 202 while communicating with the SeNB 203.Alternatively, the SeNB 203 may send a separate request of keeping theother bearer(s) unreleased to the MME 214.

FIG. 10 illustrates an embodiment of a method for the MeNB 202 of thewireless communication system 200 to add the SeNB resources by switchingthe bearer from the MeNB 202 to the SeNB 203, based on the X2 approach.

In some embodiments, blocks 1001 to 1011 are similar to blocks 901 to9011 and may not be reiterated for simplicity. In block 1012, based onX2 approach, the MeNB 202 may deliver the packet data received from theSeNB 203 to the core network system 204, and vice versa.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 10. For example, the communication module212 or other device may further transmit the path switch request to theMME 214 to request switching the downlink path of the EPS bearer frombetween the MeNB 202 and the core network system 204 to between the SeNB203 and the core network system 204, wherein the DRB of the EPS bearerhas already been switched from the MeNB 202 to the SeNB 203. The pathswitch request may include the list of the EPS bearer(s) whose DRB(s)have been switched. In some embodiments, the path switch request mayfurther indicate to keep other bearer(s) unreleased, wherein the otherbearer(s) may include those not listed in the request, such as the DRBsrelated to the MeNB 202 but not switched to the SeNB 203, and/or theSRBs related to the MeNB 202. In this way, the UE 201 may still beconnected to the MeNB 202 while communicating with the SeNB 203.Alternatively, the SeNB 203 may send a separate request of keeping theother bearer(s) unreleased to the MME 214.

FIG. 11 illustrates an embodiment of a method for the SeNB 203 of thewireless communication system 200 to add the SeNB resources by switchingthe bearer from the MeNB 202 to the SeNB 203 based on the S1 approach.

In some embodiments, according to the S1 approach, the UE 201 maycommunication with the core network system 204 over the DRB of the EPSbearer established through the MeNB 202 for the macro cell. Under somecircumstances such as when the UE 201 moving into the small cell, theMeNB 202 may make the decision of adding the SeNB resources by switchingthe DRB from the MeNB 202 to the SeNB 203.

In block 1101, the communication module 213 or other device of SeNB 203may receive the request of adding the SeNB resources from the MeNB 202.The request may be embodied as the SeNB addition request or the smallcell addition request (not illustrated in FIG. 11), and may include,without limitation, information element (IE) such as cause for the SeNBaddition or the small cell addition, a list of E-RABs to be setup,characteristics of the DRB, UE security capabilities for S1 approach,security context for S1 approach, and/or others. In block 1102, thecommunication module 213 or other device may perform the admissioncontrol to determine whether the request is acceptable or not. Inresponse to the determination that the request is acceptable andrelevant E-RAB bearer recourses can be granted, in block 1103, thecommunication module 213 may send the acknowledgement message to theMeNB 202, such as the SeNB addition request ACK or the small celladdition request ACK (not illustrated in FIG. 11). The SeNB additionrequest ACK or the small cell addition request ACK may include, withoutlimitation, a list of admitted E-RABs, a list of not admitted E-RABs, atransparent container to be sent to the UE for the SeNB addition or thesmall cell addition, and/or others. The transparent container mayinclude, without limitation, a new C-RNTI for identifying the UE 201 bythe SeNB 203, secondary eNB security algorithm identifiers for selectedsecurity algorithms, a dedicated random access channel (RACH) preamble,access parameters, system information blocks (SIBs) parameters, and/orothers.

In block 1104, the communication module 213 or other device may receivethe SN status transfer message and packet data forwarded from the MeNB202. In some embodiments, the MeNB 202 may convey uplink PDCP (packetdata convergence protocol) SN receiver status and/or downlink PDCP SNtransmitter status of E-RABs for which PDCP status preservation applies.In block 1105, the communication module 213 or other device may bufferthe packet data received from the MeNB 202, for example, in the memoryor the data storage of the SeNB 203.

After UE 201 synchronizing with the SeNB 203 and being able to accessthe small cell, in block 1106, the communication module 213 (e.g., RRClayer 2132) or other device may receive theRRCconnectionreconfigurationcomplete message from the UE 201.Alternatively, the communication module 213 (e.g., RRC layer 2132) mayreceive the SeNB addition complete message or the small cell additioncomplete message (not illustrated in FIG. 11) from the MeNB 202, eitherof which may inform the SeNB 203 of the completion of adding the SeNBresources.

When the UE 201 can access the small cell, it may transmit the uplinkpacket to the SeNB 203 over the DRB through the small cell, which may betransferred by the SeNB 203 to the core network system 204. In block1107, the communication module 213 or other device may transmit the pathswitch request to the MME 214 to request switching the downlink path ofthe EPS bearer from between the MeNB 202 and the core network system 204to between the SeNB 203 and the core network system 204, wherein the DRBof the EPS bearer has already been switched from between the MeNB 202 tothe SeNB 203. The path switch request may include the list of the EPSbearer(s) whose DRBs have been switched. In some embodiments, the pathswitch request may further indicate to keep other bearer(s) unreleased,wherein the other bearer(s) may include those not listed in the request,such as the DRBs related to the MeNB 202 and not switched to the SeNB203, and/or the SRBs related to the MeNB 202. In this way, the UE 201may still be connected to the MeNB 202 while communicating with the SeNB203. Alternatively, the MeNB 202 may send the separate request ofkeeping the other bearer(s) unreleased, in which case the block 1107 maybe omitted.

After the core network system 204 switches the downlink path of the EPSbearer from the MeNB 202 to the SeNB 203, in block 1108, thecommunication module 213 or other device may receive the acknowledgementmessage from the core network system 204 (e.g., the MME 214), such asthe path switch request ACK. In block 1109, the communication module 213or other device may receive the end marker from the MeNB 202 indicatingthe end of data forwarding from the MeNB 202 to the SeNB 203.

After completion of switching the DRB and adding the SeNB resources,based on the S1 approach, the UE 201 may communicate with the corenetwork system 204 over the DRB through the SeNB 203.

FIG. 12 illustrates an embodiment of a method for the SeNB 203 of thewireless communication system 200 to add the SeNB resources by switchingthe bearer from the MeNB 202 to the SeNB 203 based on the X2 approach.

In some embodiments, blocks 1201 to 1206 are similar to blocks 1101 to1106 and may not be reiterated for simplicity. In block 1207, aftercompletion of switching the DRB and adding the SeNB resources, based onthe X2 approach, the UE 201 may communicate with the SeNB 203 over theDRB through the small cell, which may further connect with the corenetwork 204 via the MeNB 202. In other words, based on the X2 approach,the communication module 213 or other device may forward the packetdata, which was received from the UE 201, to the MeNB 202 for furthertransmission to the core network 204, and vice versa.

FIG. 13 illustrates an embodiment of a signalling procedure for thewireless communication system 200 to release SeNB resources by switchinga bearer from the SeNB 203 to the MeNB 202, based on the S1 approach.

As illustrated in FIG. 13, based on the S1 approach, the UE 201 maycommunicate packet data with the core network system 204 over a DRB ofan EPS bearer through the SeNB 203 for the small cell. Under the dualconnectivity, the UE 201 may communicate another packet data with theMeNB 202 over another DRB of another EPS bearer or communicate asignalling with the MeNB 202 over a SRB through the MeNB 202.

In some embodiments, the MeNB 202 may transmit a message related tomeasurement control to the UE 201 (signalling 1301). In someembodiments, the message may configure the UE measurement proceduresaccording to area restriction information. Measurements provided by theMeNB 202 may assist the function controlling the UE's connectionmobility. In response to the message, the UE 201 may perform themeasurement procedures and transmit a measurement report to the MeNB 202(signalling 1302).

Based on the measurement report, the MeNB 202 may make a decision ofreleasing the SeNB resources by switching the DRB from the SeNB 203 tothe MeNB 202. This may happen under certain circumstances, such as whenthe UE 201 moving out of the coverage of the small cell. As illustratedin FIG. 13, the decision may be called as a carrier aggregation (CA)decision. On the other hand, although not being illustrated in FIG. 13,it should be understood that the MeNB 202 may make a decision of notreleasing the SeNB resources, for example, when the measurement reportindicates that the radio quality in the small cell is good enough.

In response to the decision of releasing the SeNB resources, the MeNB202 may send to the SeNB 203 for the small cell a request of releasingthe SeNB resources (signalling 1303). The request may be embodied as aSeNB release request or a small cell release request (not illustrated inFIG. 13), and may include, without limitation, information necessary forpreparing the DRB switch, such as elements (IE) like cause for the SeNBrelease or the small cell release, a list of E-RABs to be switched,characteristics of the DRB (such as DRB parameters, TNL addressinformation, and/or others), UE C-RNTI in the small cell, UE securitycapabilities for S1 approach, security context for S1 approach, and/orothers. Then, the SeNB 203 may perform an admission control to determinewhether the request is acceptable or not. In response to a determinationthat the request is acceptable, the SeNB 203 may send an acknowledgementmessage to the MeNB 202, such as a small cell release request ACK(signalling 1304). The SeNB release request ACK or the small cellrelease request ACK may include, without limitation, information such asthe C-RNTI, the cause for the SeNB release or the small cell release, alist of admitted E-RABs including TNL address information for therespective E-RAB, a list of not admitted E-RABs, a transparent containerto be sent to the UE for the SeNB release or the small cell release,and/or others.

Upon receipt of the acknowledgment message, the MeNB 202 may transmit tothe UE 201 a message of reconfiguring the RRC connection to release theSeNB resources by switching the DRB from the SeNB 203 to the MeNB 202(signalling 1305). The message may be embodied as, without limitation, aRRCconnectionreconfiguration message and may include SeNB releaseinformation or small cell release information (i.e., SeNB releaseinformation) to inform the UE 201 that the SeNB resources are going tobe released.

The SeNB 203 may deliver buffered and in transit packet data to the MeNB202. Before forwarding the packet data, the SeNB 203 may transfer SNstatus message to the MeNB 202 (signalling 1306). In some embodiments,the SeNB 203 may convey uplink PDCP (packet data convergence protocol)SN receiver status and/or downlink PDCP SN transmitter status of E-RABsfor which PDCP status preservation applies. The MeNB 202 may buffer thepacket data received from the SeNB 203 in a memory or a data storage ofthe MeNB 202.

In some embodiments, based on the information in theRRCconnectionreconfiguration message, the UE 201 may reconfigure the DRBto detach from the SeNB 203 in order to release the SeNB resources.Then, the UE 201 may transmit a RRCconnectionreconfigurationcompletemessage to the MeNB 202 to inform that the RRC connectionreconfiguration has been completed and the SeNB resources have beensuccessfully released (signalling 1307). The MeNB 202 may then transmita SeNB resources complete message or a SeNB release complete message ora small cell release complete message (not illustrated in FIG. 13) tothe SeNB 203, which may include a UE identifier, a transactionidentifier, and/or others (Signalling 1308).

When the UE 201 can access the macro cell over the DRB, based on the S1approach, it may transmit an uplink packet to the MeNB 202 over the DRB,which may be transferred by the MeNB 203 to the core network system 204.The MeNB 202 may further transmit a path switch request to the MME 214to request switching a downlink path of the EPS bearer from between theSeNB 203 and the core network system 204 to between the MeNB 202 and thecore network system 204 (signalling 1309), wherein the DRB of the EPSbearer has already been switched from the SeNB 203 to the MeNB 202. Thepath switch request may include a list of the EPS bearer(s) whose DRB(s)have been switched. In some embodiments, the path switch request mayfurther indicate to keep other bearer(s) unreleased, wherein the otherbearer(s) may include those not listed in the request, such as the DRBsand/or the SRBs related to the MeNB 202. Alternatively, the MeNB 202 maysend a separate request of keeping the other bearer(s) unreleased to theMME 214. In other embodiments, it may be the SeNB 203, rather than theMeNB 202, which may send the path switch request to the MME 214.

Upon receipt of the path switch request, the MME 214 may transmit amodify bearer request to the S-GW 224 to request modifying the downlinkpath of the listed EPS bearer(s) to go through the MeNB 202 (signalling1310). In response to the request, the S-GW 224 may switch the downlinkpath, so that the downlink packet data can be transmitted from the corenetwork system 204 to the UE 201 through the MeNB 202 for the macrocell, based on the S1 approach. In some embodiments, the S-GW 224 mayfurther send an End Marker to the SeNB 203 indicating an end of downlinkpacket data transmission on the old path (signalling 1311). The SeNB 203may send another End Marker to the MeNB 202 indicating an end of dataforwarding from the SeNB 203 to the MeNB 202 (signalling 1312).

After the completion of the bearer modification, the S-GW 224 may sendwith a modify bearer response to the MME 214 (signalling 1313), whichmay trigger the MME 214 to transmit an acknowledgement message to theMeNB 202, such as a path switch request ACK (signalling 1314).

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 13. In some embodiments, it may be theSeNB 203 which makes the decision of releasing the SeNB resources. Insuch case, the SeNB release request or the small cell release requestmay be sent from the SeNB 203 to MeNB 202, and the SeNB release requestACK or the small cell release request ACK may be sent from the MeNB 202to the SeNB 203.

FIG. 14 illustrates an embodiment of a signalling procedure for thewireless communication system 200 to release the SeNB resources byswitching the bearer from the SeNB 203 to the MeNB 202, based on the X2approach.

In some embodiments, the signalling procedure of FIG. 14 may be similaras that of FIG. 13. However, due to the X2 approach, before releasingthe SeNB resources, the UE 201 may receive/transmit the packet datafrom/to SeNB 203 over the DRB of the EPS bearer, and the SeNB 203 maythen communicate the packet data with the core network system 204through the MeNB 202. In view of this, based on the X2 approach, theremay be no need for the SeNB 203 to deliver the buffered and in transitpacket data to the MeNB 202.

Moreover, in some embodiments, after the completion of the RRCconnection reconfiguration to switch the DRB from the SeNB 203 to theMeNB 202 (signalling 1406), the transmissions of the packet data betweenthe UE 201 and the core network system 204 over the EPS bearer may onlyneed to go through the MeNB 202. In this way, there may be no need torequest the core network system 204 to modify the downlink path of theEPS bearer from the SeNB 203 to the MeNB 202.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 14. In some embodiments, it may be theSeNB 203 which makes the decision of releasing the SeNB resources. Insuch case, the SeNB release request or the small cell release requestmay be sent from the SeNB 203 to MeNB 202, and the SeNB release requestACK or the small cell release request ACK may be sent from the MeNB 202to the SeNB 203.

FIG. 15 illustrates an embodiment of a method for the UE 201 of thewireless communication system 200 to release the SeNB resources byswitching the bearer from the SeNB 203 to the MeNB 202.

In block 1501, the communication module 211 or other device of the UE201 may communicate with the core network system 204 over the DRB of theEPS bearer through the SeNB 203 for the small cell. Under the dualconnectivity, the communication module 211 or other device maycommunicate another packet data with the MeNB 202 over another DRB ofanother EPS bearer through the MeNB 202 or communicate the signallingwith the MeNB 202 over the SRB through the MeNB 202.

In block 1502, the communication module 211 or other device may receivethe message related to the measurement control from the MeNB 202. Insome embodiments, the message may configure the UE measurementprocedures according to area restriction information. Measurementsprovided by the MeNB 202 may assist the function controlling the UE'sconnection mobility. In response to the message, the communicationmodule 211 or other device may perform the measurement and may transmitthe measurement report to the MeNB 202 in block 1503. Based on themeasurement report, the MeNB 202 may make the decision of releasing theSeNB resources by switching the DRB from the SeNB 203 to the MeNB 202.This may happen under certain circumstances, such as when the UE 201moving out of the coverage of the small cell. On the other hand,although not being illustrated in FIG. 15, it should be understood thatthe MeNB 202 may make the decision of not releasing the SeNB resources,for example, when the measurement report indicates that the radioquality in the small cell is good enough.

In response to the decision of releasing the small cell, thecommunication module 211 (e.g., RRC layer 2112) or other device mayreceive, from the MeNB 202 or SeNB 203, the message of reconfiguring theRRC connection to release the small cell by switching the DRB from theSeNB 203 to the MeNB 202, in block 1504. The request may be embodied as,without limitation, a RRCconnectionreconfiguration message and mayinclude small cell release information (i.e., SeNB release informationor small cell release information) to inform the UE 201 that the smallcell is going to be released.

In some embodiments, based on the information in the RRC connectionreconfiguration message, the communication module 211 (e.g., RRC layer2112) or other device may reconfigure the DRB to detach from the SeNB203 in order to release the SeNB resources. After detaching from theSeNB 203, the communication module 211 (e.g., RRC layer 2112) or otherdevice may transmit the RRCconnectionreconfigurationcomplete message tothe MeNB 202 to inform that the RRC connection reconfiguration has beencompleted and the SeNB resources has been successfully released, inblock 1506. In block 1507, the communication module 211 or other devicemay start to communicate the packet data with the core network system204 over the DRB through the MeNB 202.

FIG. 16 illustrates an embodiment of a method for the MeNB 202 of thewireless communication system 200 to release the SeNB resources byswitching the bearer from the SeNB 203 to the MeNB 202, based on the S1approach.

In some embodiments, based on the S1 approach, the UE 201 maycommunication with the core network system 204 over the DRB of the EPSbearer through the SeNB 203 for the small cell. Under the dualconnectivity, the UE 201 may communicate another packet data with theMeNB 202 over another DRB of another EPS bearer or communicate thesignalling with the MeNB 202 over the SRB.

As illustrated in FIG. 16, in some embodiments, the communication module212 or other device of the MeNB 202 may transmit the message related tothe measurement control to the UE 201. In some embodiments, the messagemay configure the UE measurement procedures according to arearestriction information. Measurements provided by the MeNB 202 mayassist the function controlling the UE's connection mobility. Inresponse to the message, the UE 201 may perform the measurementprocedures. In block 1602, the communication module 212 or other devicemay receive the measurement report from the UE 201. In block 1603, basedon the measurement report, the communication module 212 or other devicemay make the decision of releasing the SeNB resources by switching theDRB from the SeNB 203 to the MeNB 202. This may happen under certaincircumstances, such as when the UE 201 moving out of the coverage of thesmall cell. On the other hand, although not being illustrated in FIG.16, it should be understood that the MeNB 202 may make the decision ofnot releasing the SeNB resources, for example, when the measurementreport indicates that the radio quality in the small cell is not goodenough.

In some embodiments, in response to the decision of releasing the SeNBresources, the communication module 212 or other device may send therequest of releasing the SeNB resources to the SeNB 203, in block 1604.The request may be embodied as the SeNB release request or the smallcell release request (not illustrated in FIG. 16), and may include,without limitation, information necessary for preparing the DRB switch,such as elements (IE) like cause for the SeNB release request or thesmall cell release, a list of E-RABs to be switched, characteristics ofthe DRB, UE C-RNTI in the small cell, UE security capabilities for S1approach, security context for S1 approach, and/or others.

In block 1605, the communication module 212 or other device may receivethe acknowledgement message from the SeNB 203, if the SeNB 203 decidesthat the SeNB release request or the small cell release request isacceptable. The acknowledgement message may be embodied as the SeNBrelease request ACK or the small cell release request ACK, and mayinclude, without limitation, information such as the C-RNTI, the causefor the SeNB release or the small cell release, a list of admittedE-RABs, a list of not admitted E-RABs, a transparent container to besent to the UE for SeNB release or the small cell release, and/orothers.

In some embodiments, upon receipt of the acknowledgment message, thecommunication module 212 (e.g., RRC layer 2122) or other device maytransmit to the UE 201 the message of reconfiguring the RRC connectionto release the SeNB resources by switching the DRB from the small cellto the macro cell, in block 1606. The message may be embodied as,without limitation, a RRCconnectionreconfiguration message and mayinclude the SeNB release information or the small cell releaseinformation (e.g., SeNB release information) to inform the UE 201 thatthe small cell is going to be released.

In some embodiments, before the SeNB 203 begins to deliver the bufferedand in-transit packet data to the MeNB 202, the communication module 212or other device may receive the SN status transfer message from the SeNB203, in block 1607. In some embodiments, the SeNB 203 may convey uplinkPDCP (packet data convergence protocol) SN receiver status and/ordownlink PDCP SN transmitter status of E-RABs for which PDCP statuspreservation applies. The communication module 212 or other device mayreceive the packet data forwarded from the SeNB 203 in block 1608, andmay buffer the packet data in the MeNB 202 in block 1609, for example,in the memory or the data storage of the MeNB 202.

After the UE 201 detaches from the SeNB 203, the communication module212 (e.g., RRC layer 2122) or other device may receive, from the UE 201,the RRCconnectionreconfigurationcomplete message informing that the RRCconnection reconfiguration has been completed and the SeNB resourceshave been successfully released, in block 1610. In block 1611, thecommunication module 212 or other device may transmit the SeNB releaserequest complete message or the small cell release complete message (notillustrated in FIG. 16) to the SeNB 203.

When the UE 201 can access the macro cell over the DRB, based on the S1approach, the communication module 212 or other device may receive theuplink packet data from the UE 201 and then transfer it to the corenetwork system 204 over the uplink path of the EPS bearer in block 1612.In block 1613, the communication module 212 or other device may furthertransmit the path switch request to the MME 214 to request switching thedownlink path of the EPS bearer from between the SeNB 203 and the corenetwork system 204 to between the MeNB 202 and the core network system204, wherein the DRB of the EPS bearer has already been switched fromthe SeNB 203 to the MeNB 202. The path switch request may include thelist of the EPS bearer(s) whose DRB(s) have been switched. In someembodiments, the path switch request may further indicate to keep otherbearer(s) unreleased, wherein the other bearer(s) may include those notlisted in the request, such as the DRBs and/or the SRBs related to theMeNB 202. Alternatively, the MeNB 202 may send a separate request ofkeeping the other bearer(s) unreleased to the MME 214. In otherembodiments, it may be the SeNB 203, rather than the MeNB 202, which maysend the path switch request to the MME 214.

After the S-GW 224 modifies the downlink path of the EPS bearer to gothrough the MeNB 202, based on the S1 approach, the communication module212 or other device may receive the downlink packet data from the corenetwork system 204 and then transfer it to the UE 201 over the downlinkpath of the EPS bearer, in block 1614. In block 1615, the communicationmodule 212 or other device may receive the End Marker from the SeNB 203,which may indicate the end of data forwarding from the SeNB 203 to theMeNB 202. In block 1616, the communication module 212 or other devicemay receive from MME 224 the acknowledgement message to the patch switchrequest, such as the path switch request ACK.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 16. In some embodiments, it may be theSeNB 203 which may make the decision of releasing the SeNB resources. Insuch case, the SeNB release request or the small cell release requestmay be sent from the SeNB 203 to MeNB 202, rather than from the MeNB 202to the SeNB 203, and the SeNB release request ACK or the small cellrelease ACK may be sent from the MeNB 202 to the SeNB 203, rather thanfrom the SeNB 203 to the MeNB 202.

FIG. 17 illustrates an embodiment of the method for the MeNB 202 of thewireless communication system 200 to release the SeNB resources byswitching the bearer from the SeNB 203 to the MeNB 202, based on the X2approach.

In some embodiments, the method of FIG. 17 may be similar as that ofFIG. 16, for example, blocks 1701 to 1706 may be similar as the blocks1601 to 1606, and blocks 1707 to 1708 may be similar as blocks 1610 to1611. However, due to the X2 approach, before releasing the SeNBresources, the UE 201 may receive/transmit the packet data from/to SeNB203 over the DRB of the EPS bearer, and the SeNB 203 maytransmit/receive the packet data to/from the core network system 204through the MeNB 202. In view of this, based on the X2 approach, theremay be no need for the SeNB 203 to deliver the buffered and in transitpacket data to the MeNB 202.

In some embodiments, after the completion of the RRC connectionreconfiguration to switch the DRB from the SeNB 203 to the MeNB 202, thetransmissions of the packet data between the UE 201 and the core networksystem 204 over the EPS bearer may only need to go through the MeNB 202.In this case, there may be no need to request the core network system204 to modify the downlink path of the EPS bearer from the SeNB 203 tothe MeNB 202.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 17. In some embodiments, it may be theSeNB 203 which may make the decision of releasing the SeNB resources. Insuch case, the SeNB resources release request or the small cell releaserequest (not illustrated in FIG. 17) may be sent from the SeNB 203 toMeNB 202, rather than from the MeNB 202 to the SeNB 203, and the SeNBrelease request ACK or the small cell release ACK (not illustrated inFIG. 17) may be sent from the MeNB 202 to the SeNB 203, rather than fromthe SeNB 203 to the MeNB 202.

FIG. 18 illustrates an embodiment of a method for the SeNB 203 of thewireless communication system 200 to release the SeNB resources byswitching the bearer from the SeNB 203 to the MeNB 202, based on the S1approach.

In some embodiments, based on the S1 approach, the UE 201 maycommunication with the core network system 204 over the DRB of the EPSbearer through the SeNB 203 for the small cell. Under the dualconnectivity, the UE 201 may communicate another packet data with theMeNB 202 over another DRB of another EPS bearer or communicate asignalling with the MeNB 202 over a SRB. In certain circumstances, suchas when the UE 201 moving out of the coverage of the small cell back, itmay be decided to release the SeNB resources by switching the DRB fromthe small cell to the macro cell.

In block 1801, the communication module 213 or other device of the SeNB203 may receive from the MeNB 202 the request of releasing the SeNBresources. The request may be embodied as a SeNB release request or thesmall cell release request, and may include, without limitation,information necessary for preparing the DRB switch, such as elements(IE) like cause for the SeNB release or the small cell release, a listof E-RABs to be switched, characterisitics of the DRB, UE C-RNTI in thesmall cell, UE security capabilities for S1 approach, security contextfor S1 approach, and/or others.

In block 1802, the communication module 213 or other device of the SeNB203 may perform the admission control to determine that the request isacceptable. However, although not being illustrated in FIG. 18, incertain circumstances, it may be determined that the request isunacceptable. In block 1803, in response to the determination that theSeNB release request or the small cell release request (not illustratedin FIG. 18) is acceptable, the communication module 213 or other devicemay transmit the SeNB release request ACK or the small cell releaserequest ACK to the MeNB 202. The SeNB release request ACK or the smallcell release request ACK may include, without limitation, informationsuch as the C-RNTI, the cause for the SeNB release or the small cellrelease, a list of admitted E-RABs, a list of not admitted E-RABs, atransparent container to be sent to the UE for the SeNB release or thesmall cell release, and/or others.

Before delivering the buffered and in-transmit packet data, thecommunication module 213 or other device may transfer SN status messageto the MeNB 202, in block 1804. In some embodiments, the SeNB 203 maytransfer uplink PDCP (packet data convergence protocol) SN receiverstatus and/or downlink PDCP SN transmitter status of E-RABs for whichPDCP status preservation applies. In block 1805, the communicationmodule 213 or other device may deliver the buffered and in transitpacket data to the MeNB 202.

In some embodiments, after the UE 201 reconfigures the RRC connection todetach from the SeNB 203 in order to release the SeNB resources, thecommunication module 213 or other device may receive the SeNB releasecomplete message or the small cell release complete message from theMeNB 202.

In some embodiments, after the downlink path of the EPS bearer isswitched from between the SeNB 203 and the core network system 204 tobetween the MeNB 202 and the core network system 204, the communicationmodule 213 or other device may receive the End Marker from the S-GW 224indicating the end of downlink packet data transmission on the old path,in block 1807. In block 1808, the communication module 213 may send theanother End Marker to the MeNB 202 indicating the end of data forwardingfrom the SeNB 203 to the MeNB 202.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 18. In some embodiments, it may be theSeNB 203 which may make the decision of releasing the SeNB resources. Insuch case, the SeNB release request or the small cell release requestmay be sent from the SeNB 203 to MeNB 202, rather than from the MeNB 202to the SeNB 203, and the SeNB release request ACK or the small cellrelease ACK may be sent from the MeNB 202 to the SeNB 203, rather thanfrom the SeNB 203 to the MeNB 202. In some embodiments, thecommunication module 213 or other device may further transmit to the MME214 the path switch request of switching the downlink path of the EPSbearer from between the SeNB 203 and the core network system 204 tobetween the MeNB 202 and the core network system 204, wherein the DRB ofthe EPS bearer has already been switched from the SeNB 203 to the MeNB202. The path switch request may include the list of the EPS bearer(s)whose DRB(s) have been switched. In some embodiments, the path switchrequest may further indicate to keep other bearer(s) unreleased, whereinthe other bearer(s) may include those not listed in the request, such asthe DRBs and/or the SRBs related to the MeNB 202.

FIG. 19 illustrates an embodiment of a method for the SeNB 203 of thewireless communication system 200 to release the SeNB resources byswitching the bearer from the SeNB 203 to the MeNB 202, based on the X2approach.

In some embodiments, the method of FIG. 19 may be similar as that ofFIG. 18. For example, blocks 1902 to 1904 may be similar as the blocks1801 to 1803, and block 1905 may be similar as block 1806. However, dueto the X2 approach, before releasing the SeNB resources, thecommunication module 213 or other device may receive/transmit the packetdata from/to UE 201 over the DRB of the EPS bearer, and then maycommunicate the packet data with the core network system 204 through theMeNB 202, in block 1901. In view of this, based on the X2 approach,there may be no need for the SeNB 203 to deliver the buffered and intransit packet data to the MeNB 202.

Moreover, in some embodiments, after the completion of the RRCconnection reconfiguration to switch the DRB from the SeNB 203 to theMeNB 202, the transmissions of the packet data between the UE 201 andthe core network system 204 over the EPS bearer may only need to gothrough the MeNB 202. In this way, there may be no need to request thecore network system 204 to modify the downlink path of the EPS bearerfrom the SeNB 203 to the MeNB 202.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 19. In some embodiments, it may be theSeNB 203 which may make the decision of releasing the SeNB resources. Insuch case, the SeNB resources release request or the small cell releaserequest (not illustrated in FIG. 19) may be sent from the SeNB 203 toMeNB 202, rather than from the MeNB 202 to the SeNB 203, and the SeNBresources release request ACK or the small cell release request ACK (notillustrated in FIG. 19) may be sent from the MeNB 202 to the SeNB 203,rather than from the SeNB 203 to the MeNB 202.

FIG. 20 illustrates an embodiment of a signalling procedure for thewireless communication system 200 to switch the SeNB resources byswitching a bearer from a source SeNB to a target SeNB, based on the S1approach.

As illustrated in FIG. 20, the wireless communication system 200 maycomprise the UE 201, the MeNB 202, a source SeNB 2030 for a source smallcell, a target SeNB 2040 for a target small cell, and the core networksystem 204 made up by the MME 214, the S-GW 224 and others. In someembodiments, based on the S1 approach, the UE 201 may be dual-connectedwith the MeNB 202 and the source SeNB 2030. Similarly as the SeNB 203,the source SeNB 2030 may include a communication module 2031, and/orothers. The communication module 2031 may receive or transmit asignalling/packet from/to the UE 201, MeNB 202, target SeNB 2040 and/orthe core network system 204 of the wireless communication system 200. Insome embodiments, the communication module 2031 may further generate,process and/or control the signalling/packet and/or other communicationsfrom/to the source SeNB 2030. Details about functionalities of thecommunication module 2031 may be provided in the following descriptions.Although not being illustrated in FIG. 20, the communication module 2031may further include several layer implementations, such as a physicallayer module, a L2 layer module, a radio resource communication (RRC)layer module, a non-access stratum (NAS) layer module, and/or others.

Similarly, the target SeNB 2040 may include a communication module 2041,and/or others. The communication module 2041 may receive or transmit asignalling/packet from/to the UE 201, MeNB 202, source SeNB 2030 and/orthe core network system 204 of the wireless communication system 200. Insome embodiments, the communication module 2041 may further generate,process and/or control the signalling/packet and/or other communicationsfrom/to the source SeNB 2030. Details about functionalities of thecommunication module 2041 may be provided in the following descriptions.Although not being illustrated in FIG. 20, the communication module 2041may further include several layer implementations, such as a physicallayer module, a L2 layer module, a radio resource communication (RRC)layer module, a non-access stratum (NAS) layer module, and/or others.

In some embodiments, based on the S1 approach, the UE 201 maycommunicate packet data from/to the source SeNB 2030 for the sourcesmall cell over a DRB of an EPS bearer. Under the dual-connectivity, theUE 201 may communicate another packet data from/to the MeNB 202 onanother DRB of another EPS bearer, or communicate signalling with theMeNB 202 on a SRB.

The MeNB 202 may transmit a message related to measurement control tothe UE 201 (signalling 2001). In some embodiments, the message mayconfigure the UE measurement procedures according to area restrictioninformation. Measurements provided by the MeNB 202 may assist thefunction controlling the UE's connection mobility. In response to themessage, the UE 201 may perform the measurement procedures and transmita measurement report to the MeNB 202 (signalling 2002).

Based on the measurement report, the MeNB 202 may make a decision ofswitching the SeNB resources by switching the DRB from the source SeNB2030 to the target SeNB 2040. This may happen under certaincircumstances, such as when the UE 201 moving from the source small cellto the target small cell. As illustrated in FIG. 20, the decision may becalled as a carrier aggregation (CA) decision. On the other hand,although not being illustrated in FIG. 20, it should be understood thatthe MeNB 202 may make a decision of not switching the SeNB resources,for example, when the measurement report indicates that the radioquality in the source small cell is good enough.

In response to the decision of switching the SeNB resources, the MeNB202 may send a request of switching the SeNB resources to the targetSeNB 2040 for the target small cell (signalling 2003), as well as to thesource SeNB 2040 for the source small cell (signalling 2005). Therequest may be embodied as a SeNB switch request or a small cell switchrequest (not illustrated in FIG. 20), and may include, withoutlimitation, information necessary for preparing the DRB switch, such aselements (IE) like TYPE field indicating whether the SeNB receiving themessage may add the DRB (i.e., the target SeNB) or release the DRB(i.e., the source SeNB), cause for the SeNB switch or the small cellswitch, a list of E-RABs to be setup or released, characteristics of theDRB (such as DRB parameters, TNL address information, and/or others), aUE C-RNTI in the source small cell or the target small cell, UE securitycapabilities for S1 approach, security context for S1 approach, and/orothers.

In response to the SeNB switch request or the small cell switch request,the target SeNB 2040 may perform an admission control to determinewhether the request is acceptable or not, namely, whether it isadmittable to add the DRB into the target small cell. In response to adetermination that the request is acceptable, the target SeNB 2040 maysend a message to the MeNB 202, such as a SeNB switch request ACK or asmall cell switch request ACK (not illustrated in FIG. 20) (signalling2004). The SeNB switch request ACK or the small cell switch request ACKmay include, without limitation, information such as the C-RNTI, thecause for the SeNB switch or the small cell switch, a list of admittedE-RABs including TNL address information for the respective E-RAB, alist of not admitted E-RABs, a transparent container to be sent to theUE for SeNB release or the small cell release, and/or others.

On the other hand, the source SeNB 2030 may perform another admissioncontrol to determine whether the SeNB switch request or the small cellswitch request is acceptable or not, namely, whether it is admittable torelease the DRB from the source small cell. In response to adetermination that the request is acceptable, the source SeNB 2030 maysend a message to the MeNB 202, such as a SeNB switch request ACK or asmall cell switch request ACK (not illustrated in FIG. 20) (signalling2006). The SeNB switch request ACK or the small cell switch request ACKmay include, without limitation, information such as the C-RNTI, thecause for the SeNB switch or the small cell switch, a list of admittedE-RABs including TNL address information for the respective E-RAB, alist of unadmitted E-RABs, a transparent container to be sent to the UEfor the SeNB release or the small cell release, and/or others.

Upon receipt of the acknowledgment messages from the source SeNB 2030and the target SeNB 2040, the MeNB 202 may transmit to the UE 201 amessage of reconfiguring the RRC connection to switch the SeNB resourcesby switching the DRB from the source small cell to the target small cell(signalling 2007). The request may be embodied as, without limitation, aRRCconnectionreconfiguration message and may include informationnecessary for switching the small cell, such as the sources SeNBinformation, the source small cell information, the target SeNBinformation, target small cell information and/or others.

In some embodiments, in order to trigger the delivery of buffered andin-transit packet data from the source SeNB 2030 to the target SeNB2040, the MeNB 202 may transmit a SeNB SN status transfer message or asmall cell SN status transfer message (not illustrated in FIG. 20) tothe source SeNB 2030 to request it to transfer the buffered andin-transit packet data to the target SeNB 2040 (signalling 2008). TheSeNB SN status transfer message or the small cell SN status transfermessage may include, without limitation, the UE RNTI in the target smallcell, the target SeNB information such as a target SeNB identifier, thetarget small cell information such as a target small cell identifier,and others. Then, the source SeNB 2030 may start to deliver the bufferedand in-transit packet data to the target SeNB 2040. Before forwardingthe packet data, the source SeNB 2030 may transfer a SN status messageto the target SeNB 2040 (signalling 2009). In some embodiments, thesource SeNB 2030 may convey uplink PDCP (packet data convergenceprotocol) SN receiver status and/or downlink PDCP SN transmitter statusof E-RABs for which PDCP status preservation applies. The target SeNB2040 may buffer the packet data received from the SeNB 203, for example,in a memory or data storage of the target SeNB 2040.

In some embodiments, based on the information in theRRCconnectionreconfiguration message, the UE 201 may reconfigure the RRCconnection to detach from the source SeNB 2030 and synchronize to thetarget SeNB 2040 in order to switch from the source SeNB 2030 to thetarget SeNB 2040. For example, the UE 201 may perform thesynchronization to the target SeNB 2040 and access the target small cellvia RACH, following a contention-free or contention-based proceduredepending on whether a dedicated preamble was indicated or not.

After synchronizing with the target SeNB 2040 and being able to accessthe target small cell, the UE 201 may transmit a RRC connectionreconfiguration complete message to the MeNB 202 to inform that the RRCconnection reconfiguration has been completed and the SeNB resources orthe small cell have been successfully switched (signalling 2010). TheMeNB 202 may then transmit a SeNB switch complete message or a smallcell switch complete message (not illustrated in FIG. 20) to the sourceSeNB 2030 (signalling 2011) and the target SeNB 2040 (signalling 2012).Alternatively, the UE 201 may send theRRCconnectionreconfigurationcomplete message to the MeNB 202 as well asthe target SeNB 2040, so that the SeNB switch complete message or thesmall cell switch complete message from the MeNB 202 to the target SeNB2040 can be omitted.

When the UE 201 can access the target small cell, based on the S1approach, it may transmit an uplink packet to the target SeNB 2040 overthe DRB, which may be transferred by the target SeNB 2040 to the corenetwork system 204. The target SeNB 2040 may further transmit a pathswitch request to the MME 214 to request switching a downlink path ofthe EPS bearer from between the source SeNB 2030 and the core networksystem 204 to between the target SeNB 2040 and the core network system204 (signalling 2013), wherein the DRB of the EPS bearer has alreadybeen switched from the source SeNB 2030 to the target SeNB 2040. Thepath switch request may include a list of the EPS bearer(s) whose DRB(s)have been switched. In some embodiments, the path switch request mayfurther indicate to keep other bearer(s) unreleased, wherein the otherbearer(s) may include those not listed in the request, such as the DRBsand/or the SRBs related to the MeNB 202. Alternatively, the MeNB 202 maysend a separate request of keeping the other bearer(s) unreleased to theMME 214. In other embodiments, it may be the MeNB 202 rather than thetarget SeNB 2040 which may send the path switch request to the MME 214.

Upon receipt of the path switch request, the MME 214 may transmit amodify bearer request to the S-GW 224 to request modifying the downlinkpath of the listed EPS bearer(s) to go through the target SeNB 2040(signalling 2014). In response to the request, the S-GW 224 may switchthe downlink path, so that the downlink packet data can be transmittedfrom the core network system 204 to the UE 201 through the target SeNB2040, based on the S1 approach. In some embodiments, the S-GW 224 mayfurther send an End Marker to the source SeNB 2030 indicating an end ofdownlink packet data transmission on the old path (signalling 2015). Thesource SeNB 2030 may send an End Marker to the target SeNB 2040indicating an end of data forwarding from the source SeNB 2030 to thetarget SeNB 2040 (signalling 2016).

After the completion of the bearer modification, the S-GW 224 may sendwith a modify bearer response to the MME 214 (signalling 2017), whichmay trigger the MME 214 to transmit an acknowledgement message to thetarget SeNB 2040, such as a path switch request ACK (signalling 2018).

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 20. In some embodiments, it may be thesource SeNB 2030 rather than the MeNB 202 which makes the decision ofswitching the SeNB resources or the small cell. In such case, the SeNBswitch request or the small cell switch request may be sent from thesource SeNB 2030 to MeNB 202 as well as the target SeNB 2040, and theSeNB switch request ACK or the small cell switch request ACK may be sentfrom the MeNB 202 and the target SeNB 2040 to the source SeNB 2030.

FIG. 21 illustrates an embodiment of a signalling procedure for thewireless communication system 200 to switch the SeNB resources byswitching the bearer from the source SeNB 2030 to the target SeNB 2040,based on the X2 approach.

In some embodiments, the signalling procedure of FIG. 21 may be similaras that of FIG. 20. For example, signalling 2101 to 2107 may be similaras signalling 2001 to 2007, and signalling 2109 to 2111 may be similaras signalling 2010 to 2012. However, due to the X2 approach, beforeswitching the DRB of the EPS bearer from the source SeNB 2030 to thetarget SeNB 2040, the source SeNB 2030 may communicate the packet datawith the core network system 204 through the MeNB 202. Moreover, in someembodiments, after the completion of the RRC connection reconfigurationto switch the DRB from the source SeNB 2030 to the target SeNB 2040, thetransmissions of the packet data between the target SeNB 2040 and thecore network system 204 over the EPS bearer may still need to go throughthe MeNB 202. In this way, there may be no need to request the corenetwork system 204 to modify the downlink path of the EPS bearer fromthe SeNB 2030 to the target SeNB 2040. In other words, the signalling2013 to 2018 in FIG. 20 may be omitted from the FIG. 21.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 21. In some embodiments, it may be thesource SeNB 2030 rather than the MeNB 202 which makes the decision ofswitching the SeNB resources or the small cell. In such case, the SeNBrelease request or the small cell release request may be sent from thesource SeNB 2030 to MeNB 202 as well as the target SeNB 2040, and thethe SeNB release request ACK or the small cell release request ACK maybe sent from the MeNB 202 and the target SeNB 2040 to the source SeNB2030.

FIG. 22 illustrates an embodiment of a method for the UE 201 of thewireless communication system 200 to switch the SeNB resources or thesmall cell by switching the bearer from the source SeNB 2030 to thetarget SeNB 2040.

In some embodiments, in block 2201, the communication module 211 orother device of the UE 201 may communicate packet data from/to thesource SeNB 2030 of the source small cell over the DRB of the EPSbearer. Under the dual connectivity, the communication module 211 orother device may communicate another packet data from/to the MeNB 202over another DRB of another EPS bearer or communicate the signallingwith the MeNB 202 over the SRB.

In block 2202, the communication module 211 or other device may receivea message related to the measurement control from the MeNB 202. In someembodiments, the message may configure the UE measurement proceduresaccording to area restriction information. Measurements provided by theMeNB 202 may assist the function controlling the UE's connectionmobility. In response to the message, the communication module 211 orother device of UE 201 may perform the measurement and may transmit themeasurement report to the MeNB 202 in block 2203. Based on themeasurement report, the MeNB 202 or source SeNB 2030 may make thedecision of switching the SeNB resources or the small cell by switchingthe DRB from the source SeNB 2030 for the source small cell to thetarget SeNB 2040 for the target small cell. This may happen undercertain circumstances, such as when the UE 201 moving from the sourcesmall cell to the target small cell. On the other hand, although notbeing illustrated in FIG. 22, it should be understood that the MeNB 202may make a decision of not switching the SeNB resources or the smallcell, for example, when the measurement report indicates that the radioquality in the source small cell is good enough.

In response to the decision of switching the SeNB resources or the smallcell, the communication module 211 (e.g., RRC layer) or other device mayreceive, from the MeNB 202, the message of reconfiguring the RRCconnection to switch the SeNB resources or the small cell by switchingthe DRB from the source SeNB 2030 to the target SeNB 2040, in block2204. The request may be embodied as, without limitation, aRRCconnectionreconfiguration message and may include informationnecessary for switching the SeNB resources or the small cell, such asthe source SeNB information, source small cell information, the targetSeNB information, the target small cell information, and/or others.

In some embodiments, based on the information in theRRCconnectionreconfiguration message, the communication module 211 orother device may reconfigure the RRC connection to detach from thesource SeNB 2030 and synchronize with the target SeNB 2040 in order toswitch the small cell, in block 2205. For example, the UE 201 mayperform the synchronization to the target SeNB 2040 and access thetarget small cell via RACH, following a contention-free orcontention-based procedure depending on whether a dedicated preamble wasindicated or not.

After synchronizing with the target SeNB 2040 and being able to accessthe target small cell, the communication module 211 (e.g., RRC layer) orother device may transmit the RRCconnectionreconfigurationcompletemessage to the MeNB 202 and/or the target SeNB 2040 to inform that theRRC connection reconfiguration has been completed and the SeNB resourcesor the small cell has been successfully switched, in block 2206. Inblock 2207, the communication module 211 or other device may communicatethe packet data with the core network system 204 over the DRB throughthe target SeNB 2040.

FIG. 23 illustrates an embodiment of a method for the MeNB 202 of thewireless communication system 200 to switch the SeNB resources or thesmall cell by switching the bearer from the source SeNB 2030 to thetarget SeNB 2040, based on the S1 approach.

In some embodiments, based on the S1 approach, the UE 201 maycommunicate packet data with the core network system 204 over the DRB ofthe EPS bearer through the source SeNB 2030 of the source small cell.Under the dual connectivity, the UE 201 may communicate another packetdata with the MeNB 202 over another DRB of another EPS bearer orcommunicate the signalling with the MeNB 202 over the SRB.

As illustrated in FIG. 23, in some embodiments, the communication module212 or other device of the MeNB 202 may transmit the message related tomeasurement control to the UE 201, in block 2301. In some embodiments,the message may configure the UE measurement procedures according toarea restriction information. Measurements provided by the MeNB 202 mayassist the function controlling the UE's connection mobility. In block2302, the communication module 212 or other device may receive themeasurement report from the UE 201. In block 2303, based on themeasurement report, the control module 222 of the MeNB 202 may make thedecision of switching the SeNB resources or the small cell by switchingthe DRB from the source small cell to the target small cell. This mayhappen under certain circumstances, such as when the UE 201 moving fromthe source small cell to the target small cell. Although not beingillustrated in FIG. 23, based on the measurement report, the MeNB 202may make a different decision, i.e., not switching the small cell.

In some embodiments, in response to the decision of switching the SeNBresources or the small cell, the communication module 212 or otherdevice may send the request of switching the SeNB resources or the smallcell to the target SeNB 2040, in block 2304. The request may be embodiedas the SeNB switch request or the small cell switch request (notillustrated in FIG. 23), and may include, without limitation,information necessary for preparing the DRB switch, such as elements(IE) like TYPE field indicating whether the SeNB receiving the messagemay add the DRB (i.e., the target SeNB) or release the DRB (i.e., thesource SeNB), cause for the SeNB switch or the small cell switch, a listof E-RABs to be setup or released, characteristics of the E-RABs (suchas E-RAB parameters, TNL address information, and/or others), a UEC-RNTI in the source small cell or the target small cell, UE securitycapabilities for S1 approach, security context for S1 approach, and/orothers.

In some embodiments, in block 2305, the communication module 212 orother device may receive the message from the target SeNB 2040, if thetarget SeNB 2040 decides that the SeNB switch request or the small cellswitch request (not illustrated in FIG. 23) is acceptable. The messagemay be embodied as the SeNB switch request ACK or the small cell switchrequest ACK (not illustrated in FIG. 23), and may include, withoutlimitation, information such as the C-RNTI, the cause for the SeNBswitch or the small cell switch, a list of admitted E-RABs including TNLaddress information for the respective E-RAB, a list of not admittedE-RABs, a transparent container to be sent to the UE for the SeNBrelease or the small cell release, and/or others.

In some embodiments, on the other hand, the communication module 212 orother device may send the SeNB switch request or the small cell switchrequest (not illustrated in FIG. 23) to the source SeNB 2030 in block2306, and may receive the SeNB switch request ACK or the small cellswitch request ACK (not illustrated in FIG. 23) from the source SeNB2030 in block 2307.

In some embodiments, upon receipt of the acknowledgment messages fromthe source SeNB 2030 and the target SeNB 2040, the communication module212 (e.g., RRC layer) or other device may transmit to the UE 201 themessage of reconfiguring the RRC connection to switch the small cell byswitching the DRB from the source SeNB 2030 to the target SeNB 2040, inblock 2308. The request may be embodied as, without limitation, aRRCconnectionreconfiguration message and may include informationnecessary for switching the SeNB resources or the small cell, such asthe source SeNB information, the source small cell information, thetarget SeNB information, the target small cell information and/orothers.

In some embodiments, in order to trigger the delivery of buffered andin-transmit packet data from the source SeNB 2030 to the target SeNB2040, the communication module 212 or other device may transmit the SeNBSN status transfer message or the small cell SN status transfer message(not illustrated in FIG. 23) to the source SeNB 2030 to request thetransfer of the buffered and in-transit packet data to the target SeNB2040, in block 2309. The SeNB SN status transfer message or the smallcell SN status transfer message may include, without limitation, the UERNTI in the target small cell, the target small cell information such asthe target small cell identifier, the target SeNB information such asthe target SeNB identifier, and/or others.

After UE 201 successfully synchronizes with the target SeNB 2040 and isable to access the target small cell, the communication module 212(e.g., RRC layer) or other device may receive theRRCconnectionreconfiguration complete message from the UE 201 that mayinform that the RRC connection reconfiguration has been completed andthe SeNB resources or the small cell have been successfully switched, inblock 2310. The communication module 212 or other device may thentransmit the SeNB switch complete message or the small cell switchcomplete message (not illustrated in FIG. 23) to the source SeNB 2030and the target SeNB 2040, in block 2311.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 23. For example, in some embodiments, ifthe UE 201 sends the RRCconnectionreconfigurationcomplete message to theMeNB 202 as well as the target SeNB 2040, the SeNB switch completemessage or the small cell switch complete message from the MeNB 202 tothe target SeNB 2040 can be omitted. For another example, it may be thesource SeNB 2030 rather than the MeNB 202 which makes the decision ofswitching the SeNB resources or the small cell. In such case, the SeNBrelease request or the small cell release request may be sent from thesource SeNB 2030 to MeNB 202 as well as the target SeNB 2040, and theSeNB release ACK or the small cell release ACK may be sent from the MeNB202 and the target SeNB 2040 to the source SeNB 2030. For yet anotherexample, the communication module 212 or other device may furthertransmit the path switch request to the MME 214 to request switching thedownlink path of the EPS bearer from between the source SeNB 2030 andthe core network system 204 to between the target SeNB 2040 and the corenetwork system 204, wherein the DRB of the EPS bearer has already beenswitched from the source SeNB 2030 to the target SeNB 2040. The pathswitch request may include the list of the EPS bearer(s) whose DRB(s)have been switched. In some embodiments, the path switch request mayfurther indicate to keep other bearer(s) unreleased, wherein the otherbearer(s) may include those not listed in the request, such as the DRBsand/or the SRBs related to the MeNB 202.

FIG. 24 illustrates an embodiment of a method for the MeNB 202 of thewireless communication system 200 to switch the SeNB resources or thesmall cell by switching the bearer from the source SeNB 2030 to thetarget SeNB 2040, based on the X2 approach.

In some embodiments, the method of FIG. 24 may be similar as that ofFIG. 23. For example, blocks 2401 to 2408 may be similar as blocks 2301to 2308, and blocks 2411-2412 may be similar as blocks 2310-2311.However, due to the X2 approach, before switching the DRB of the EPSbearer from the source SeNB 2030 to the target SeNB 2040, the sourceSeNB 2030 may communicate the packet data with the core network system204 through the MeNB 202.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 24. For example, in some embodiments, ifthe UE 201 sends the RRCconnectionreconfigurationcomplete message to theMeNB 202 as well as the target SeNB 2040, the SeNB switch completemessage or the small cell switch complete message (not illustrated inFIG. 24) from the MeNB 202 to the target SeNB 2040 can be omitted. Foranother example, it may be the source SeNB 2030 rather than the MeNB 202which makes the decision of switching the SeNB resources or the smallcell. In such case, the SeNB release request or the small cell releaserequest (not illustrated in FIG. 24) may be sent from the source SeNB2030 to the MeNB 202 as well as to the target SeNB 2040. Further, theSeNB release request ACK or the small cell release ACK (not illustratedin FIG. 24) may be sent from the MeNB 202 and the target SeNB 2040 tothe source SeNB 2030.

FIG. 25 illustrates an embodiment of a method for the source SeNB 2030of the wireless communication system 200 to switch the SeNB resources orthe small cell by switching the bearer from the source SeNB 2030 to thetarget SeNB, based on the S1 approach.

In some embodiments, based on the S1 approach, the UE 201 maycommunicate the packet data with the core network system 204 over theDRB of the EPS bearer through the source SeNB 2030 of the source smallcell. Under the dual connectivity, the UE 201 may communicate anotherpacket data with the MeNB 202 over another DRB of another EPS bearer orcommunicate the signalling with the MeNB 202 over the SRB.

In some embodiments, the MeNB 202 may make the decision of switching theSeNB resources or the small cell by switching the DRB from the sourceSeNB 2030 to the target SeNB 2040. This may happen under certaincircumstances, such as when the UE 201 moving from the source small cellto the target small cell. In such case, the communication module 2031 orother device of the source SeNB 2030 may receive, from the MeNB 202, therequest of switching the SeNB resources or the small cell, in block2501. The request may be embodied as the SeNB switch request or thesmall cell switch request (not illustrated in FIG. 25), and may include,without limitation, information necessary for preparing the DRB switch,such as elements (IE) like TYPE field indicating whether the SeNBreceiving the message may add the DRB (i.e., the target SeNB) or releasethe DRB (i.e., the source SeNB), cause for the SeNB switch or the smallcell switch, a list of E-RABs to be setup or released, characteristicsof E-RAB (such as E-RAB parameters, TNL address information, and/orothers), a UE C-RNTI in the source small cell or the target small cell,UE security capabilities for S1 approach, security context for S1approach, and/or others.

In block 2502, the communication module 2031 or other device may performthe admission control and determine that the request is acceptable.Moreover, in bock 2502, the communication module 2031 or other devicemay send the message to the MeNB 202, such as the SeNB switch requestACK or the small cell switch request ACK (not illustrated in FIG. 25).The SeNB switch request ACK or the small cell switch request ACK mayinclude, without limitation, information such as the C-RNTI, the causefor the SeNB switch or the small cell switch, a list of admitted E-RABsincluding TNL address information for the respective E-RAB, a list ofunadmitted E-RABs, a transparent container to be sent to the UE for theSeNB release or the small cell release, and/or others.

On the other hand, although not being illustrated in FIG. 25, it shouldbe understood that the source SeNB 2030 may make a decision of notadmitting the SeNB switch request or the small cell switch request, forexample, when the measurement report indicates that the radio quality inthe small cell is good enough

In block 2503, the communication module 2031 or other device mayreceive, from the MeNB 202, the SeNB SN status transfer message or thesmall cell SN status transfer message (not illustrated in FIG. 25) whichmay trigger the delivery of buffered and in-transmit packet data fromthe source SeNB 2030 to the target SeNB 2040. In response to the SeNB SNstatus transfer message or the small cell SN status transfer message,the communication module 2031 or other device may send the SN statusmessage to the target SeNB 2040. In some embodiments, the communicationmodule 2031 or other device may convey uplink PDCP (packet dataconvergence protocol) SN receiver status and/or downlink PDCP SNtransmitter status of E-RABs for which PDCP status preservation applies.Then, in block 2505, the communication module 2031 or other device mayforward the buffered and in-transit packet data to the target SeNB 2040.

After the UE 201 detaches from the source small cell and synchronizes tothe target small cell, the communication module 2031 or other device mayreceive, from the MeNB 202, the SeNB switch complete message or thesmall cell switch complete message (not illustrated in FIG. 25) in block2506, which may inform that the SeNB switch or the small cell switch hasbeen completed. In block 2507, the communication module 2031 or otherdevice may receive, from the core network system 204 (e.g., S-GW 224),the End Marker indicating the end of downlink packet data transmissionfrom the core network system 204 to the source SeNB 2030 on the oldpath. In block 2508, the communication module 2031 or other device maysend, to the target SeNB 2040, the End Marker indicating the end of dataforwarding from the source SeNB 2030 to the target SeNB 2040.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 25. For example, it may be the sourceSeNB 2030 rather than the MeNB 202 which makes the decision of switchingthe small cell. In such case, the SeNB release request or the small cellrelease request may be sent from the source SeNB 2030 to MeNB 202 aswell as to the target SeNB 2040, and the SeNB release ACK or the smallcell release ACK may be sent from the MeNB 202 and the target SeNB 2040to the source SeNB 2030.

FIG. 26 illustrates an embodiment of a method for the source SeNB 2030of the wireless communication system 200 to switch the bearer from thesource SeNB 2030 to the target SeNB 2040, based on the X2 approach.

In some embodiments, due to the X2 approach, before switching the DRB ofthe EPS bearer from the source SeNB 2030 to the target SeNB 2040, thesource SeNB 2030 may communicate the packet data between the UE 201 andthe core network system 204 through the MeNB 202. In other words, thesource SeNB 2030 may receive the packet data from the UE 201 andtransmit it to the core network system 204 through the MeNB 202, and/orreceive the packet data from the core network system through the MeNB202 and transmit it to the UE 201. Further, under the dual connectivity,the UE 201 may communicate another packet data with the MeNB 202 overanother DRB of another EPS bearer or communicate the signalling with theMeNB 202 over the SRB.

In some embodiments, the communication module 2031 or other device ofthe source SeNB 2030 may receive, from the MeNB 202, the request ofswitching the SeNB resources or the small cell in block 2601. Therequest may be embodied as the SeNB switch request or the small cellswitch request (not illustrated in FIG. 26), and may include, withoutlimitation, information necessary for preparing the DRB switch, such aselements (IE) like TYPE field indicating whether the SeNB receiving themessage may add the DRB (i.e., the target SeNB) or release the DRB(i.e., the source SeNB), cause for the SeNB switch or the small cellswitch, a list of E-RABs to be setup or released, characteristics ofE-RAB (such as E-RAB parameters, TNL address information, and/orothers), a UE C-RNTI in the source small cell or the target small cell,UE security capabilities for S1 approach, security context for S1approach, and/or others.

In block 2602, the communication module 2031 or other device may performthe admission control and determine that the request is acceptable.Moreover, in bock 2602, the communication module 2031 may send themessage to the MeNB 202, such as the SeNB switch request ACK or thesmall cell switch request ACK (not illustrated in FIG. 26). The SeNBswitch request ACK or the small cell switch request ACK may include,without limitation, information such as the C-RNTI, the cause for theSeNB switch or the small cell switch, a list of admitted E-RABsincluding TNL address information for the respective E-RABs, a list ofunadmitted E-RABs, a transparent container to be sent to the UE for theSeNB release or the small cell release, and/or others. On the otherhand, although not being illustrated in FIG. 26, it should be understoodthat the source SeNB 2030 may make the decision of not admitting theSeNB switch request or the small cell switch request.

In some embodiments, after the UE 201 detaches from the source smallcell and synchronizes to the target small cell, the communication module2031 or other device may receive, from the MeNB 202, the SeNB switchcomplete message or the small cell switch complete message (notillustrated in FIG. 26) in block 2603, which may inform that the SeNBresources switch or the small cell switch has been completed.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 26. For example, it may be the sourceSeNB 2030 rather than the MeNB 202 which makes the decision of switchingthe SeNB resources or the small cell. In such case, the SeNB releaserequest or the small cell release request may be sent from the sourceSeNB 2030 to MeNB 202 as well as to the target SeNB 2040. Further, theSeNB release request ACK or the small cell release request ACK may besent from the MeNB 202 and the target SeNB 2040 to the source SeNB 2030.

FIG. 27 illustrates an embodiment of a method for the target SeNB 2040of the wireless communication system 200 to switch the bearer from thesource SeNB 2030 to the target SeNB 2040, based on the S1 approach.

In some embodiments, based on the S1 approach, before switching thesmall cell, the UE 201 may communicate the packet data with the corenetwork system 204 over the DRB of the EPS bearer through the sourceSeNB 2030 of the source small cell. Under the dual connectivity, the UE201 may communicate another packet data with the MeNB 202 over anotherDRB of another EPS bearer or communicate the signalling with the MeNB202 over the SRB.

In some embodiments, it may be decided to switch the SeNB resources orthe small cell by switching the DRB from the source SeNB 2030 to thetarget SeNB 2040. This may happen under certain circumstances, such aswhen the UE 201 moving from the source small cell to the target smallcell. In such case, the communication module 2041 or other device of thetarget SeNB 2040 may receive the request of switching the DRB from theMeNB 202 or the source SeNB 2030 in block 2701. The request may beembodied as the SeNB switch request or the small cell switch request(not illustrated in FIG. 27), and may include, without limitation,information necessary for preparing the DRB switch, such as elements(IE) like TYPE field indicating whether the SeNB receiving the messagemay add the DRB (i.e., the target SeNB) or release the DRB (i.e., thesource SeNB), cause for the SeNB switch or the small cell switch, a listof E-RABs to be setup or released, characteristics of E-RAB (such asE-RAB parameters, TNL address information, and/or others), a UE C-RNTIin the source small cell or the target small cell, UE securitycapabilities for S1 approach, security context for S1 approach, and/orothers.

In block 2702, the communication device 2041 or other device may performthe admission control and determine that the request is acceptable. Inblock 2703, the communication module 2041 or other device may send themessage to the MeNB 202 or the source SeNB 2030, such as the SeNB switchrequest or the small cell switch request ACK (not illustrated in FIG.27). The SeNB switch request ACK or the small cell switch request ACKmay include, without limitation, information such as the C-RNTI, thecause for the SeNB switch or the small cell switch, a list of admittedE-RABs (such as E-RAB parameters, TNL address information, and/orothers), a list of unadmitted E-RABs, a transparent container to be sentto the UE for the SeNB release or the small cell release, and/or others.On the other hand, although not being illustrated in FIG. 27, it shouldbe understood that the target SeNB 2040 may make the decision of notadmitting the SeNB switch request or the small cell switch request.

In some embodiments, in block 2704, the communication module 2041 orother device may receive the SeNB SN status transfer message or thesmall cell SN status transfer message (not illustrated in FIG. 27) fromthe source SeNB 2030. In some embodiments, the source SeNB 2030 mayconvey uplink PDCP (packet data convergence protocol) SN receiver statusand/or downlink PDCP SN transmitter status of E-RABs for which PDCPstatus preservation applies. Then, in block 2705, the communicationmodule 2041 or other device may receive the buffered and in-transitpacket data from the source SeNB 2040, and in block 2706, the targetSeNB 2040 may buffer the packet data, for example, in the memory or thedata storage of the target SeNB 2040.

In some embodiments, in response to the RRCconnectionreconfigurationmessage, the UE 201 may reconfigure the RRC connection to detach fromthe source SeNB 2030 and synchronize with the target SeNB 2040 in orderto switch the DRB from the source small cell to the target small cell,in block 2707. For example, the UE 201 may perform the synchronizationto the target SeNB 2040 and access the target small cell via RACH,following a contention-free or contention-based procedure depending onwhether a dedicated preamble was indicated or not.

After synchronizing with the UE 201 which may be able to access thetarget small cell, in block 2708, the communication module 2041 (e.g.,RRC layer) or other device may receive the RRC connectionreconfiguration complete message from the UE 201. Alternatively, thecommunication module 2041 (e.g., RRC layer) or other device may receive,from the MeNB 202, the SeNB switch complete message or the small cellswitch complete message (not illustrated in FIG. 27), either of whichmay inform that the DRB has been successfully switched from the sourcesmall cell to the target small cell. When the UE 201 can access thetarget small cell, based on the S1 approach, the communication module2041 or other device may receive/transmit packet data from/to the UE201, in block 2709.

In some embodiments, in block 2710, the communication module 2041 orother device may further transmit the path switch request to the MME 214to request switching the downlink path of the EPS bearer from betweenthe source SeNB 2030 and the core network system 204 to between thetarget SeNB 2040 and the core network system 204, wherein the DRB of theEPS bearer has already been switched from the source SeNB 2030 to thetarget SeNB 2040. The path switch request may include a list of the EPSbearer(s) whose DRB(s) has been switched. In some embodiments, the pathswitch request may further indicate to keep other bearer(s) unreleased,wherein the other bearer(s) may include those not listed in the request,such as the DRBs and/or the SRBs related to the MeNB 202. Alternatively,the target SeNB 2040 or the MeNB 202 may send a separate request ofkeeping the other bearer(s) unreleased to the MME 214. In otherembodiments, it may be the MeNB 202 rather than the target SeNB 2040which may send the path switch request to the MME 214.

With modification of the downlink path of the EPS bearer to go throughthe target SeNB 2040, the target SeNB 2040 may be able to receive thepacket data from the core network system 204, such as the S-GW 224. Inthis way, the communication path between the UE 201 and the core networksystem 204 through the target SeNB 2040 has been completed. Further, thecommunication module 2041 or other device may receive theacknowledgement message, such as the patch switch request ACK from theMME 214, in block 2711. In block 2712, the communication module 2041 orother device may receive the End Marker from the source SeNB 2030indicating the end of data forwarding from the source SeNB 2030 to thetarget SeNB 2040.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 27. For example, it may be the sourceSeNB 2030 rather than the MeNB 202 which makes the decision of switchingthe SeNB resources or the small cell. In such case, the SeNB releaserequest or the small cell release request may be sent from the sourceSeNB 2030 to MeNB 202 as well as to the target SeNB 2040. Further, theSeNB release ACK or the small cell release ACK may be sent from the MeNB202 and the target SeNB 2040 to the source SeNB 2030.

FIG. 28 illustrates an embodiment of a method for the target SeNB 2040of the wireless communication system 200 to switch the SeNB resources orthe small cell by switching the bearer from the source SeNB 2030 to thetarget SeNB 2040, based on the X2 approach.

In some embodiments, the method of FIG. 28 may be similar as that ofFIG. 27. For example, blocks 2801 to 2803 and blocks 2804-2805 may besimilar as blocks 2701 to 2703, and blocks 2707 to 2708. However, due tothe X2 approach, before switching the DRB of the EPS bearer from thesource SeNB 2030 to the target SeNB 2040, the source SeNB 2030 maycommunicate the packet data with the core network system 204 through theMeNB 202. Moreover, in some embodiments, after the completion of the RRCconnection reconfiguration to switch the DRB from the source SeNB 2030to the target SeNB 2040, the transmissions of the packet data betweenthe target SeNB 2040 and the core network system 204 over the EPS bearermay still need to go through the MeNB 202. In this way, there may be noneed to forward the buffer and in transit packet data from the sourceSeNB 2030 to the target SeNB 2040, or to request the core network system204 to modify the downlink path of the EPS bearer from the SeNB 2030 tothe target SeNB 2040. In other words, the blocks 2704-2706 and blocks2710-2712 of FIG. 27 may be omitted from the FIG. 28.

Other embodiments may implement other modifications and variations to onthe method as depicted in FIG. 28. For example, it may be the sourceSeNB 2030 rather than the MeNB 202 which makes the decision of switchingthe SeNB resources or the small cell. In such case, the SeNB releaserequest or the small cell release request may be sent from the sourceSeNB 2030 to MeNB 202 as well as to the target SeNB 2040, and the SeNBrelease ACK or the small cell release ACK may be sent from the MeNB 202and the target SeNB 2040 to the source SeNB 2030.

FIG. 29 schematically illustrates an example system 2900 in accordancewith various embodiments. The system 2900 may comprise one or moreprocessor(s) 2904, system control logic 2908 coupled with at least oneof the processor(s) 2904, system memory 2912 coupled with system controllogic 2908, non-volatile memory (NVM)/storage 2916 coupled with systemcontrol logic 2908, and a network interface 2920 coupled with systemcontrol logic 2908.

Processor(s) 2904 may include one or more single-core or multi-coreprocessors. Processor(s) 2904 may include any combination ofgeneral-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, baseband processors, etc.). In anembodiment in which the system 2900 implements the UE 201, processors(s)2904 may be configured to execute one or more embodiment(s) asillustrated in FIG. 2-4, 6-8, 13-15, or 20-22 in accordance with variousembodiments. In an embodiment in which the system 2900 implements theMeNB 202, processor(s) 2904 may be configured to execute one or moreembodiment(s) as illustrated in FIG. 2-3, 5-7, 9-10, 13-14, 16-17,20-21, or 23-24 in accordance with various embodiments. In an embodimentin which the system 2900 implements the SeNB 203, processor(s) 2904 maybe configured to execute one or more embodiment(s) as illustrated inFIG. 2, 6-7, 11-14, or 18-19 in accordance with various embodiments. Inan embodiment in which the system 2900 implements the source SeNB 2030,processor(s) 2904 may be configured to execute one or more embodiment(s)as illustrated in FIG. 2, 20-21 or 25-26 in accordance with variousembodiments. In an embodiment in which the system 2900 implements thetarget SeNB 2040, processor(s) 2904 may be configured to execute one ormore embodiment(s) as illustrated in FIG. 2, 20-21 or 27-28 inaccordance with various embodiments.

System control logic 2908 for one embodiment may include any suitableinterface controllers to provide for any suitable interface to at leastone of the processor(s) 2904 and/or to any suitable device or componentin communication with system control logic 2908.

System control logic 2908 for one embodiment may include one or morememory controller(s) to provide an interface to system memory 2912.System memory 2912 may be used to load and store data and/orinstructions, for example, for system 2900. System memory 2912 for oneembodiment may include any suitable volatile memory, such as suitabledynamic random access memory (DRAM), for example.

NVM/storage 2916 may include one or more tangible, non-transitorycomputer-readable media used to store data and/or instructions, forexample. NVM/storage 2916 may include any suitable non-volatile memory,such as flash memory, for example, and/or may include any suitablenon-volatile storage device(s), such as one or more hard disk drive(s)(HDD(s)), one or more compact disk (CD) drive(s), and/or one or moredigital versatile disk (DVD) drive(s), for example.

The NVM/storage 2916 may include a storage resource physically part of adevice on which the system 2900 is installed or it may be accessible by,but not necessarily a part of, the device. For example, the NVM/storage2916 may be accessed over a network via the network interface 2920.

System memory 2912 and NVM/storage 2916 may respectively include, inparticular, temporal and persistent copies of instructions 2924.Instructions 2924 may include instructions that when executed by atleast one of the processor(s) 2904 result in the system 2900implementing one or more of method(s) as described with reference toFIGS. 4-5, 8-12, 15-19, and 22-28. In various embodiments, instructions2924, or hardware, firmware, and/or software components thereof, mayadditionally/alternatively be located in the system control logic 2908,the network interface 2920, and/or the processor(s) 2904.

Network interface 2920 may have a transceiver (e.g., the communicationmodule 211, 212 or 213 in FIG. 2, and the communication module 2031 or2041 in FIGS. 20-21) to provide a radio interface for system 2900 tocommunicate over one or more network(s) and/or with any other suitabledevice. In various embodiments, the communication module 211, 212 or 213may be integrated with other components of system 2900. For example, thecommunication module 211, 212, 213, 2031 or 2041 may include a processorof the processor(s) 2904, memory of the system memory 2912, NVM/Storageof NVM/Storage 2916, and/or a firmware device (not being illustrated)having instructions that when executed by at least one of theprocessor(s) 2904 result in the system 2900 implementing one or more ofmethod(s) as described with reference to FIGS. 4-5, 8-12, 15-19, and22-28.

Network interface 2920 may include any suitable hardware and/orfirmware. Network interface 2920 may include a plurality of antennas toprovide a multiple input, multiple output radio interface. Networkinterface 2920 for one embodiment may include, for example, a networkadapter, a wireless network adapter, a telephone modem, and/or awireless modem.

For one embodiment, at least one of the processor(s) 2904 may bepackaged together with logic for one or more controller(s) of systemcontrol logic 2908. For one embodiment, at least one of the processor(s)2904 may be packaged together with logic for one or more controllers ofsystem control logic 2908 to form a System in Package (SiP). For oneembodiment, at least one of the processor(s) 2904 may be integrated onthe same die with logic for one or more controller(s) of system controllogic 2908. For one embodiment, at least one of the processor(s) 2904may be integrated on the same die with logic for one or morecontroller(s) of system control logic 2908 to form a System on Chip(SoC).

The system 2900 may further include input/output (I/O) devices 2932. TheI/O devices 2932 may include user interfaces designed to enable userinteraction with the system 2900, peripheral component interfacesdesigned to enable peripheral component interaction with the system2900, and/or sensors designed to determine environmental conditionsand/or location information related to the system 2900.

In various embodiments, the user interfaces could include, but are notlimited to, a display (e.g., a liquid crystal display, a touch screendisplay, etc.), a speaker, a microphone, one or more cameras (e.g., astill camera and/or a video camera), a flashlight (e.g., a lightemitting diode flash), and a keyboard.

In various embodiments, the peripheral component interfaces may include,but are not limited to, a non-volatile memory port, an audio jack, and apower supply interface.

In various embodiments, the sensors may include, but are not limited to,a gyro sensor, an accelerometer, a proximity sensor, an ambient lightsensor, and a positioning unit. The positioning unit may also be partof, or interact with, the network interface 2920 to communicate withcomponents of a positioning network, e.g., a global positioning system(GPS) satellite.

In various embodiments, the system 2900 may be a mobile computing devicesuch as, but not limited to, a laptop computing device, a tabletcomputing device, a netbook, a mobile phone, etc. In other embodiments,the system 2900 may be an eNB, such as, but not limited to, a mastereNB, a secondary eNB, etc. In various embodiments, system 2900 may havemore or less components, and/or different architectures.

The disclosure may include various example embodiments disclosed below.

In example embodiment 1, a method, apparatus or system to be employed bya user equipment (UE) may comprise a communication module to communicatewith a core network on a first bearer through a first evolved Node B(eNB), receive, from the first eNB, a first message of reconfiguring aradio resource control (RRC) connection to establish a second bearerbetween the UE and the core network through a second eNB; synchronize,in response to the message, with the second eNB in order to establishthe second bearer; and communicate with the core network on the secondbearer, and continue communicating other with the core network on thefirst bearer.

In example embodiment 2, the first eNB according to the exampleembodiment 1 may be a master eNB (MeNB).

In example embodiment 3, the second eNB according to any of the exampleembodiments 1-2 may be a secondary eNB (SeNB).

In example embodiment 4, the communication module according to any ofthe example embodiments 1-3 may further transmit, to the first eNB, asecond message informing that the RRC connection reconfiguration hasbeen completed.

In example embodiment 5, the first message according to any of theexample embodiments 1-4 may comprise bearer context information relatedto the second bearer and eNB information related to the second eNBinformation.

In example embodiment 6, the first message according to any of theexample embodiments 1-5 may comprise a new cell-radio network temporaryidentifier (C-RNTI), security algorithm identifiers, dedicated RACHpreamble for a second cell associated to the second eNB, and/or others.

In example embodiment 7, a method, apparatus or system to be employed bya first evolved Node B (eNB), may comprise a communication module tocommunicate with a user equipment (UE) and a core network on a firstbearer through the first eNB; receive, from the UE or the core network,a first request of establishing a second bearer between the UE and thecore network; transmit, to a second eNB, a second request of adding thesecond eNB for the second bearer; and receive, from the second eNB, aresponse to the second request to acknowledge that the second eNB can beadded for the second bearer.

In example embodiment 8, the first eNB according to the exampleembodiment 7 may be a master eNB (MeNB).

In example embodiment 9, the second eNB according to any of the exampleembodiments 7-8 may be a secondary eNB (SeNB).

In example embodiment 10, the second request according to any of theexample embodiments 7-9 may be a SeNB addition request comprising acause for the SeNB addition, a list of bearers to be setup, UE securitycapabilities, security context, and/or others.

In example embodiment 11, the response according to any of the exampleembodiments 7-10 may be a SeNB addition acknowledgment messagecomprising a list of admitted bearers, a list of not admitted bearers, atransparent container to be sent to the UE for the SeNB addition, and/orothers.

In example embodiment 12, the communication module according to any ofthe example embodiments 7-11 may further transmit, to or from the UE, amessage of reconfiguring a radio resource control (RRC) connection toestablish the second bearer, wherein the message includes bearer contextinformation related to the second bearer and eNB information related tothe second eNB.

In example embodiment 13, the message according to any of the exampleembodiments 7-12 may comprise a new cell-radio network temporaryidentifier (C-RNTI), security algorithm identifiers, dedicated randomaccess channel (RACH) preamble for a second cell associated with thesecond eNB, and/or others.

In example embodiment 14, the communication module according to any ofthe example embodiments 7-13 may further receive, from the UE, anothermessage informing that the RRC connection reconfiguration has beencompleted; and transmit, to the core network, another response to thefirst request to inform that the second bearer has been redirected tothe second eNB.

In example embodiment 15, the first eNB according to any of the exampleembodiments 7-14 may continue communicating with the UE and the corenetwork on the first bearer through the first cell, while the UE furthercommunicates with the core network on the second bearer through thesecond eNB.

In example embodiment 16, a method, apparatus or system to be employedby a first evolved Node B (eNB), may comprise a communication module toreceive, from a second eNB for a second cell, a request of adding thefirst eNB for a first bearer to be established between a user equipment(UE) and a core network; transmit, to the second eNB, a response to thefirst request to acknowledge that the first eNB can be added for thefirst bearer; synchronize with the UE in order to establish the firstbearer; and communicate with the UE and the core network on the firstbearer through the first eNB, wherein, the UE communicates with the corenetwork on a second bearer through the second eNB.

In example embodiment 17, the first eNB according to the exampleembodiment 16 may be a secondary eNB (SeNB).

In example embodiment 18, the second eNB according to any of the exampleembodiments 16-17 may be a macro eNB (MeNB).

In example embodiment 19, the first request according to any of theexample embodiments 16-18 may be a SeNB addition request comprising acause for the SeNB addition, a list of bearers to be setup, UE securitycapabilities, security context, and/or others.

In example embodiment 20, the response according to any of the exampleembodiments 16-19 may be a SeNB addition acknowledgement messagecomprising a list of admitted bearers, a list of not admitted bearers, atransparent container to be sent to the UE for SeNB addition, and/orothers.

In example embodiment 21, a method, apparatus or system to be employedby a user equipment (UE), may comprise a communication module tocommunicate with a core network on one or more data bearers through afirst evolved Node B (eNB); receive, from the first eNB, a message ofreconfiguring a radio resource control (RRC) connection to switch atleast one of the one or more data bearers from the first eNB to a secondeNB; synchronize with the second eNB, in response to the message; andcommunicate with the core network on the at least one of the databearers through the second eNB, while communicating with the first eNBon a signaling bearer through the first eNB.

In example embodiment 22, the first eNB according to the exampleembodiment 21 may be a master eNB (MeNB).

In example embodiment 23, the second eNB according to any of the exampleembodiments 21-22 may be a secondary eNB (SeNB).

In example embodiment 24, the message according to any of the exampleembodiments 21-23 may be a RRCconnectionreconfiguration messagecomprising a new cell-radio network temporary identifier (C-RNTI),second eNB security algorithm identifiers and optionally dedicatedrandom access channel (RACH) preamble, second eNB system informationblocks, and/or others.

In example embodiment 25, the communication module according to any ofthe example embodiments 21-24 may further continue communicating withthe core network on a remaining data bearer of the data bearers whichhasn't been switched from the first eNB to the second eNB.

In example embodiment 26, the communication module according to any ofthe example embodiments 21-25 may further transmit, to the first eNB orthe second eNB, another message informing that the RRC connectionreconfiguration has been completed.

In example embodiment 27, a method, apparatus or system to be employedby a first evolved Node B (eNB), may comprise a communication module tocommunicate with a user equipment (UE) and a core network on one or moredata bearers through the first eNB; transmit, to a second eNB, a firstrequest of adding a second SeNB by switching at least one of the databears from the first eNB to the second eNB; receive, from the secondeNB, a first message to acknowledge that the second eNB can be added;transmit, to the UE, a second message of reconfiguring a radio resourcecontrol (RRC) connection to switch the at least one data bearer; andcommunicate with the UE on a signaling bearer through the first eNB,while the UE communicates with the core network on the at least one databearer through the second eNB.

In example embodiment 28, the first eNB according to the exampleembodiment 27 may be a master eNB (MeNB).

In example embodiment 29, the second eNB according to any of the exampleembodiments 27-28 may be a secondary eNB (SeNB).

In example embodiment 30, the communication module according to any ofthe example embodiments 27-29 may further continue communicating withthe UE and the core network on a remaining data bear of the data bearswhich hasn't been switched from the first eNB to the second eNB.

In example embodiment 31, the communication module according to any ofthe example embodiments 27-30 may further receive, from the UE, a thirdmessage informing that the RRC connection reconfiguration has beencompleted.

In example embodiment 32, the communication module according to any ofthe example embodiments 27-31 may further transmit, to the second eNB, afourth message informing that the second SeNB has been added.

In example embodiment 33, the communication module according to any ofthe example embodiments 27-32 may further transmit, to the core network,a second request of switching a downlink path of an evolved packetsystem (EPS) bearer from between the first eNB and the core network tobetween the second eNB and the core network, wherein a data bearer ofthe EPS bearer has been switched from the first eNB to the second eNB.

In example embodiment 34, the communication module according to any ofthe example embodiments 27-33 may further transmit, to the core network,an indication to keep at least one EPB bearer not listed in the secondrequest unreleased.

In example embodiment 35, the first request according to any of theexample embodiments 27-34 may be a SeNB addition request comprisingcause for a list of bearers to be setup, UE security capabilities,security context, and/or others.

In example embodiment 36, the first message according to any of theexample embodiments 27-35 may be a SeNB addition acknowledgement messagecomprising a list of admitted bearers, a list of not admitted bearers, atransparent container to be sent to the UE for the SeNB addition, and/orothers.

In example embodiment 37, the communication module according to any ofthe example embodiments 27-36 may further receive, from the UE, ameasurement report about UE connection mobility; and determine, based onthe measurement report, to add the second SeNB.

In example embodiment 38, a method, apparatus or system to be employedby a first evolved Node B (eNB), may comprise a communication module toreceive, from a second eNB, a first request of adding the first eNB byswitching at least one of one or more data bearers from the second eNBto the first eNB, wherein a user equipment (UE) communicated with a corenetwork on the data bears through the second eNB; transmit, to thesecond eNB, a first message to acknowledge that the first eNB can beadded; synchronize with the UE in order to establishing the at least onedata bearer between the UE and the second eNB; communicate with the UEand the core network on the at least one data bearer through the firsteNB, while the UE communicates with the second eNB on a signallingbearer through second eNB.

In example embodiment 39, the first eNB according to the exampleembodiment 38 may be a secondary eNB (MeNB).

In example embodiment 40, the second eNB according to any of the exampleembodiments 38-39 may be a master eNB (SeNB).

In example embodiment 41, the UE according to any of the exampleembodiments 38-40 may continue communicating with the core network on aremaining data bear of the data bearers which hasn't been switched fromthe second eNB to the first eNB.

In example embodiment 42, the communication module according to any ofthe example embodiments 38-41 may further transmit, to the core network,a second request of switching a downlink data path of the at least onedata bearer from between the second eNB and the core network to betweenthe first eNB and the core network; receive, from the core network, asecond message to acknowledge that the downlink data path of the atleast one data bearer has been switched.

In example embodiment 43, the communication module according to any ofthe example embodiments 38-42 may further transmit, to the core network,an indication of keeping a remaining data bearer of the data bearers,which hasn't been switched from the second eNB to the first eNB,unreleased.

In example embodiment 44, the first request according to any of theexample embodiments 38-43 may be a SeNB addition request comprisingcause for a list of bearers to be setup, UE security capabilities,security context, and/or others.

In example embodiment 45, the first message according to any of theexample embodiments 38-44 may be a SeNB addition acknowledgement messagecomprising a list of admitted bearers, a list of not admitted bearers, atransparent container to be sent to the UE for the SeNB addition, and/orothers.

In example embodiment 46, a method, apparatus, or system to be employedby a user equipment (UE), may comprise a communication module tocommunicate with a first evolved Node B (eNB) on a first bearer throughthe first eNB; communicate with a second eNB on a second bearer througha second eNB; receive, from the second eNB, a first message ofreconfiguring a radio resource control (RRC) connection to switch thefirst bearer from the first eNB to the second eNB; detach from the firsteNB, in response to the first message; communicate on the first bearthrough the second eNB, while continuing communicating on the secondbearer through the second eNB.

In example embodiment 47, the first eNB according to the exampleembodiment 46 may be a secondary eNB (MeNB).

In example embodiment 48, the second eNB according to any of the exampleembodiments 46-47 may be a master eNB (SeNB).

In example embodiment 49, the first message according to any of theexample embodiments 46-48 may be a RRCconnectionreconfiguration messagecomprising a SeNB release information to inform the UE that the secondSeNB is going to be released.

In example embodiment 50, the communication module according to any ofthe example embodiments 46-49 may further transmit, to the second eNB, asecond message informing that the RRC connection reconfiguration iscompleted.

In example embodiment 51, a method, apparatus or system to be employedby a first evolved node B (eNB), may comprise a communication module tocommunicate with a user equipment (UE) on a first bearer through thefirst eNB, while the UE communicates with a second eNB on a secondbearer through the second eNB; transmit or receive, to or from a secondeNB, a first request of releasing the second eNB; receive or transmit,from or to the second eNB, a first message to acknowledge that thesecond eNB can be released; and transmit, to the UE, a second message ofreconfiguring a radio resource control (RRC) connection to switch thesecond bearer from the second eNB to the first eNB.

In example embodiment 52, the first eNB according to the exampleembodiment 51 may be a macro eNB (MeNB).

In example embodiment 53, the second eNB according to any of the exampleembodiments 51-52 may be a secondary eNB (SeNB).

In example embodiment 54, the first request according to any of theexample embodiments 51-53 may be a SeNB release request including atleast one of a cause for the SeNB release, a list of bearers to beswitched, a UE cell-radio network temporary identifier (C-RNTI) in asecond cell associated with the second eNB, UE security capabilities,security context, and/or others.

In example embodiment 55, the first message according to any of theexample embodiments 51-54 may be a SeNB release acknowledgment messageincluding at least one of a UE cell-radio network temporary identifier(C-RNTI), a cause for the SeNB release, a list of admitted bearers, alist of not admitted bearers, a transparent container to be sent to theUE for the cell release, and/or others.

In example embodiment 56, the first bearer according to any of theexample embodiments 51-55 may be a signalling bearer and/or a databearer, and the second bearer is a data bearer.

In example embodiment 57, the communication module according to any ofthe example embodiments 51-56 may further receive, from the UE, a thirdmessage informing that the RRC connection reconfiguration is completed;and transmit, to the second eNB, a fourth message informing that thesecond bearer has been released.

In example embodiment 58, the communication module according to any ofthe example embodiments 51-57 may further transmit, to a core network, asecond request of switching a downlink path of the second bearer frombetween the second eNB and the core network to between the first eNB andthe core network, wherein the second request further indicates not torelease a bearer associated with the UE and not listed in the secondrequest.

In example embodiment 59, the communication module according to any ofthe example embodiments 51-58 may further receive, from the corenetwork, a fifth message to acknowledge that the downlink data path ofthe second bearer is switched.

In example embodiment 60, a method, apparatus or system to be employedby a first evolved Node B (eNB), may comprise a communication module tocommunicate with a user equipment (UE) on a first bearer through thefirst eNB, wherein the UE further communicates on a second bearerthrough a second eNB; receive or transmit, from or to a second eNB, afirst request of releasing the first SeNB by switching the first bearerfrom the first eNB to the second eNB; transmit or receive, to or fromthe second eNB, a first message to acknowledge that the first SeNB canbe released in response to a determination that the first request isacceptable; and detach from the UE in order to release the first bearer.

In example embodiment 61, the first eNB according to the exampleembodiment 60 may be a secondary eNB (MeNB).

In example embodiment 62, the second eNB according to any of the exampleembodiments 60-61 may be a master eNB (SeNB).

In example embodiment 63, the first request according to any of theexample embodiments 60-62 may be a SeNB release request including atleast one of a cause for the SeNB release or the small cell release, alist of bearers to be switched, a UE cell-radio network temporaryidentifier (C-RNTI) in a second cell associated with the second eNB, UEsecurity capabilities, security context, and/or others.

In example embodiment 63, the first message according to any of theexample embodiments 60-62 may be a SeNB release acknowledgment messageincluding at least one of a UE cell-radio network temporary identifier(C-RNTI), a cause for the SeNB release, a list of admitted bearers, alist of not admitted bearers, a transparent container to be sent to theUE for the SeNB release, and/or others.

In example embodiment 64, the communication module according to any ofthe example embodiments 60-63 may further transmit, to a core network, asecond request of switching a downlink path of the first bearer frombetween the first eNB and the core network to between the second eNB andthe core network, wherein the second request further indicates not torelease a bearer associated with the UE and not listed in the secondrequest.

In example embodiment 65, the communication module according to any ofthe example embodiments 60-64 may further receive, from the corenetwork, a second message to acknowledge that the downlink data path ofthe first bearer is switched.

In example embodiment 66, a method, apparatus, or system to be employedby a user equipment (UE), may comprise a communication module tocommunicate with a first evolved Node B (eNB) on a first bearer througha first eNB; communicate with a second eNB on a second bearer through asecond eNB; receive, from the first eNB, a first message ofreconfiguring a radio resource control (RRC) connection to switch thesecond bearer from the second eNB to a third eNB; detach from the secondeNB and synchronizing with the third eNB, in response to the firstmessage; communicate with the third eNB on the second bearer through thethird eNB, while continuing communicating with the first eNB on thefirst bearer through the first eNB.

In example embodiment 67, the first eNB according to the exampleembodiments 66 may be a master eNB (MeNB).

In example embodiment 68, the second eNB according to any of the exampleembodiments 66-67 may be a source secondary eNB (SeNB).

In example embodiment 69, the third eNB according to any of the exampleembodiments 66-68 may be a target secondary eNB (SeNB).

In example embodiment 70, the first message according to any of theexample embodiments 66-69 may be a RRCconnectionreconfiguration messagecomprising at least one of second eNB information, third eNB informationand others.

In example embodiment 71, the communication module according to any ofthe example embodiments 66-70 may further transmit, to the first eNB orthe third eNB, a second message informing that the RRC connectionreconfiguration is completed.

In example embodiment 72, the first bearer according to any of theexample embodiments 66-71 may be a data bearer and/or a signallingbearer, and the second bearer is another data bearer.

In example embodiment 73, a method, apparatus or system to be employedby a first evolved Node B (eNB), may comprise a communication module tocommunicate with a user equipment (UE) on a first bearer through thefirst eNB, wherein the UE further communicates with a second eNB on asecond bearer through the second eNB; transmit or receive, to or from asecond eNB, a first request of switching the second eNB by switching thesecond bearer from the second eNB to a third eNB; and receive ortransmit, from or to the second eNB, a first message to acknowledge thatthe second eNB can be switched.

In example embodiment 74, the first eNB according to the exampleembodiment 73 may be a master eNB (MeNB).

In example embodiment 75, the second eNB according to any of the exampleembodiments 73-74 may be a source secondary eNB (SeNB).

In example embodiment 76, the third eNB according to any of the exampleembodiments 73-75 may be a target secondary eNB (SeNB).

In example embodiment 77, the first request according to any of theexample embodiments 73-76 may be a SeNB switch request including atleast one of a TYPE field indicating whether an eNB receiving the firstrequest adds the second bearer or release the second bearer, a cause forthe SeNB switch, a list of bearers to be setup or released, a UEcell-radio network temporary identifier (C-RNTI) in a second cellassociated with the second eNB or a third cell associated with the thirdeNB, UE security capabilities, security context, and/or others.

In example embodiment 78, the first message according to any of theexample embodiments 73-77 may be a SeNB switch request acknowledgementmessage comprising at least one of cell-radio network temporaryidentifier (C-RNTI), a cause for the SeNB switch, a list of admittedbearers, a list of not admitted bearers, a transparent container to besent to the UE for the SeNB switch, and/or others.

In example embodiment 79, the communication module according to any ofthe example embodiments 73-78 may further transmit, to the third eNB, asecond request of switching the second eNB by switching the secondbearer from the second cell to the third cell; and receive, from thethird eNB, a second message to acknowledge that the second eNB can beswitched.

In example embodiment 80, the second request according to any of theexample embodiments 73-79 may be a SeNB switch request comprising atleast one of a TYPE field indicating whether an eNB receiving themessage adds the second bearer or release the second bearer, a cause forthe small cell switch, a list of bearers to be setup or released, a UEcell-radio network temporary identifier (C-RNTI) in a second cellassociated with the second eNB or a third cell associated with the thirdeNB, UE security capabilities, security context, and/or others.

In example embodiment 81, the second message according to any of theexample embodiments 73-80 may be a SeNB switch acknowledgement messagecomprising at least one of a cell-radio network temporary identifier(C-RNTI), a cause for the SeNB switch, a list of admitted bearers, alist of unadmitted bearers, a transparent container to be sent to the UEfor SeNB switch, and/or others.

In example embodiment 82, the communication module according to any ofthe example embodiments 73-81 may further transmit, to the UE, a thirdmessage of reconfiguring a radio resource control (RRC) connection byswitching the second bearer from the second eNB to the third eNB.

In example embodiment 83, the third message according to any of theexample embodiments 73-82 may be a RRCconnectionreconfiguration messagecomprising at least one of second Enb information, third eNB informationand/or others.

In example embodiment 84, the communication module according to any ofthe example embodiments 73-83 may further receive, from the UE, a fourthmessage informing that the RRC connection reconfiguration is completed;and transmit, to the second eNB and/or the third eNB, a fifth messageinforming that the second eNB switch is completed.

In example embodiment 85, the communication module according to any ofthe example embodiments 73-84 may further transmit, to the second eNB, athird request of transferring a sequence number (SN) status from thesecond eNB to the third eNB.

In example embodiment 86, the communication module according to any ofthe example embodiments 73-85 may further transmit, to a core network, afourth request of switching a downlink path of the second bearer frombetween the second eNB and the core network to between the third eNB andthe core network.

In example embodiment 87, the fourth request according to any of theexample embodiments 73-86 may further indicate not to release a bearerassociated with the UE and not listed in the second request.

In example embodiment 88, the communication module according to any ofthe example embodiments 73-87 may further continue communicating withthe UE on the first bearer through the first eNB, while the UE furthercommunicates with the third eNB on the second bearer through the secondeNB.

In example embodiment 89, a method, apparatus or system to be employedby a first evolved Node B (eNB), may comprise a communication module tocommunicate with a user equipment on a first bearer through the firsteNB, wherein the UE further communicates with a second eNB on a secondbearer through the second eNB; receive or transmit, from or to thesecond eNB, a first request of switching the first eNB by switching thefirst bearer from the first eNB to a third eNB; and transmit or receive,to or from the second eNB, a first message to acknowledge that the firsteNB can be switched.

In example embodiment 90, the first eNB according to the exampleembodiments 89 may be a source secondary eNB (SeNB).

In example embodiment 91, the second eNB according to any of the exampleembodiments 89-90 may be a master eNB (MeNB).

In example embodiment 92, the third eNB according to any of the exampleembodiments 89-91 may be a target secondary eNB (SeNB).

In example embodiment 93, the first request according to any of theexample embodiments 89-92 may be a SeNB switch request comprising atleast one of a TYPE field indicating whether an eNB receiving themessage adds the first bearer or release the first bearer, a cause forthe SeNB switch, a list of bearers to be setup or released, a UEcell-radio network temporary identifier (C-RNTI) in a first cellassociated with the first eNB or a third cell associate with the thirdeNB, UE security capabilities, security context, and/or others.

In example embodiment 94, the first message according to any of theexample embodiments 89-93 may be a SeNB switch request acknowledgementmessage comprising at least one of cell-radio network temporaryidentifier (C-RNTI), a cause for the SeNB switch, a list of admittedbearers, a list of not admitted bearers, a transparent container to besent to the UE for the SeNB switch, and/or others.

In example embodiment 95, the communication module according to any ofthe example embodiments 89-94 may further receive, from the second eNB,a second message of transferring a sequence number (SN) status from thefirst eNB to the third eNB; and forward, in response to the secondmessage, a buffered and in transit data to the third eNB.

In example embodiment 96, the communication module according to any ofthe example embodiments 89-95 may further transmit, to a core network, athird request of switching a downlink path of the first bearer frombetween the first eNB and the core network to between the third eNB andthe core network.

In example embodiment 97, the third request according to any of theexample embodiments 89-96 may further indicate not to release a bearerassociated with the UE and not listed in the third request.

In example embodiment 98, a method, apparatus or system to be employedby a first evolved Node B (eNB), may comprise a communication module tocommunicate with a user equipment on a first bearer through the firsteNB, wherein the UE further communicates with a second eNB on a secondbearer through the second eNB; transmit, to a third eNB, a first requestof switching the first eNB by switching the first bearer from the firsteNB to the third eNB; and receive, from the third eNB, a first messageto acknowledge that the first eNB can be switched.

In example embodiment 99, the first eNB according to the exampleembodiments 98 may be a source secondary eNB (SeNB).

In example embodiment 100, the second eNB according to any of theexample embodiments 98-99 may be a master eNB (MeNB).

In example embodiment 101, the third eNB according to any of the exampleembodiments 98-100 may be a target secondary eNB (SeNB).

In example embodiment 102, the first request according to any of theexample embodiments 98-101 may be a SeNB switch request comprising atleast one of a TYPE field indicating whether an eNB receiving themessage adds the first bearer or release the first bearer, a cause forthe SeNB switch, a list of bearers to be setup or released, a UEcell-radio network temporary identifier (C-RNTI) in a first cellassociated with the first eNB or a third cell associated with the thirdeNB, UE security capabilities, security context, and/or others.

In example embodiment 103, the first message according to any of theexample embodiments 98-102 may be a SeNB switch request acknowledgementmessage comprising at least one of cell-radio network temporaryidentifier (C-RNTI), a cause for the SeNB switch, a list of admittedbearers, a list of not admitted bearers, a transparent container to besent to the UE for the SeNB switch, and/or others.

In example embodiment 104, the communication module according to any ofthe example embodiments 98-103 may further transmit, to the second eNB,a second request of switching the first eNB by switching the firstbearer from the first eNB to the third eNB; and receive, from the secondeNB, a second message to acknowledge that the first eNB can be switched.

In example embodiment 105, the second request according to any of theexample embodiments 98-104 may be a SeNB switch request comprising atleast one of a TYPE field indicating whether an eNB receiving themessage adds the first bearer or release the first bearer, a cause forthe SeNB switch, a list of bearers to be setup or released, a UEcell-radio network temporary identifier (C-RNTI) in the second cell orthe third cell, UE security capabilities, security context, and/orothers.

In example embodiment 106, the second message according to any of theexample embodiments 98-105 may be a small cell switch requestacknowledgement message comprising at least one of cell-radio networktemporary identifier (C-RNTI), a cause for the cell switch, a list ofadmitted bearers, a list of not admitted bearers, a transparentcontainer to be sent to the UE for the small cell switch, and/or others.

In example embodiment 107, the communication module according to any ofthe example embodiments 98-106 may further receive, from the second eNB,a third message of transferring a sequence number (SN) status from thefirst eNB to the third eNB; and forward, in response to the thirdmessage, a buffered and in transit data to the third eNB.

In example embodiment 108, the communication module according to any ofthe example embodiments 98-101 may further transmit, to a core network,a third request of switching a downlink path of the first bearer frombetween the first eNB and the core network to between the third eNB andthe core network.

In example embodiment 109, the third request according to any of theexample embodiments 98-108 may further indicate not to release a bearerassociated with the UE and not listed in the third request.

In example embodiment 110, a method, apparatus or system to be employedby a first eNB, may comprise a communication module to receive, from asecond eNB or a third eNB, a first request of switching a third eNB byswitching a first bearer from the third eNB to the first eNB, wherein auser equipment (UE) communicates with the third eNB on the first bearerthrough the third eNB and communicates with the second eNB on a secondbearer through the second eNB; transmit, to the second eNB or the thirdeNB, a first message to acknowledge that the third eNB can be switched;synchronize with the user equipment (UE) to establish the first bearerthrough the first eNB; and communicate with the UE on the first bearerthrough the first eNB.

In example embodiment 111, the first eNB according to the exampleembodiment 110 may be a target secondary eNB (SeNB).

In example embodiment 112, the second eNB according to any of theexample embodiments 110-111 may be a master eNB (MeNB).

In example embodiment 113, the third eNB according to any of the exampleembodiments 110-112 may be a source secondary eNB (SeNB).

In example embodiment 114, the first request according to any of theexample embodiments 110-113 may be a SeNB switch request comprising atleast one of a TYPE field indicating whether an eNB receiving themessage adds the first bearer or release the first bearer, a cause forthe SeNB switch, a list of bearers to be setup or released, a UEcell-radio network temporary identifier (C-RNTI) in a first cellassociated with the first eNB or a third cell associated with the thirdeNB, UE security capabilities, security context, and/or others.

In example embodiment 115, the first message according to any of theexample embodiments 110-114 may be a SeNB switch request acknowledgementmessage comprising at least one of cell-radio network temporaryidentifier (C-RNTI), a cause for the SeNB switch, a list of admittedbearers, a list of not admitted bearers, a transparent container to besent to the UE for the SeNB switch, and/or others.

In example embodiment 116, the communication module according to any ofthe example embodiments 110-115 may further transmit, to a core network,a second request of switching a downlink path of the first bearer frombetween the third eNB and the core network to between the first eNB andthe core network.

In example embodiment 117, the third request according to any of theexample embodiments 110-116 may further indicate not to release a bearerassociated with the UE and not listed in the second request.

Although certain embodiments have been illustrated and described hereinfor purposes of description, a wide variety of alternate and/orequivalent embodiments or implementations calculated to achieve the samepurposes may be substituted for the embodiments shown and describedwithout departing from the scope of the present disclosure. Thisapplication is intended to cover any adaptations or variations of theembodiments discussed herein. Therefore, it is manifestly intended thatembodiments described herein be limited only by the claims and theequivalents thereof.

1.-41. (canceled)
 42. One or more non-transitory, computer-readablemedia having instructions that, when executed, cause a master evolvedNode B (“MeNB”) to: select a secondary evolved Node B (“SeNB”) toestablish an evolved universal terrestrial radio access network radioaccess bearer (“E-RAB”) for dual-connectivity operation of a userequipment (“UE”); generate an addition request to request the SeNB toestablish the RAB; and cause transmission of the addition request to theSeNB.
 43. The one or more non-transitory, computer-readable media ofclaim 42, wherein the addition request includes a list of E-RABs to besetup.
 44. The one or more non-transitory, computer-readable media ofclaim 42, wherein the addition request includes security capabilities ofthe UE.
 45. the one or more non-transitory, computer-readable media ofclaim 42, wherein the addition request is an X2 message to betransmitted over an X2 interface.
 46. The one or more non-transitory,computer-readable media of claim 42, wherein the instructions, whenexecuted, further cause the MeNB to: process an addition requestacknowledgement received from the SeNB in response to the additionrequest.
 47. The one or more non-transitory, computer-readable media ofclaim 5, wherein the addition request acknowledgement includes a list ofadmitted E-RABs.
 48. The one or more non-transitory, computer-readablemedia of claim 42, wherein the instructions, when executed, furthercause the MeNB to: generate an RRC connection reconfiguration message toinclude small cell information to facilitate establishment of aconnection with the SeNB; and cause the RRC connection reconfigurationmessage to be transmitted to the UE.
 49. The one or more non-transitory,computer-readable media of claim 42, wherein the addition request is anSeNB addition request.
 50. The or more non-transitory, computer-readablemedia of claim 42, wherein the instructions, when executed, furthercause the MeNB to: generate a release request to be sent to the SeNB torequest that the SeNB release the E-RAB used by the UE fordual-connectivity operation; and cause transmission of the releaserequest to the SeNB.
 51. An apparatus comprising: communicationcircuitry to: select a secondary evolved Node B (“SeNB”) to establish anevolved universal terrestrial radio access network radio access bearer(“E-RAB”) for dual connectivity operation of a user equipment (“UE”);and generate an addition request to request the SeNB to establish theRAB; and X2 interface circuitry to cause the addition request to betransmitted to the SeNB.
 52. The apparatus of claim 51, wherein theaddition request includes a list of E-RABs to be setup.
 53. Theapparatus of claim 51, wherein the addition request includes securitycapabilities of the UE.
 54. The apparatus of claim 51, wherein theaddition request is an X2 message.
 55. The apparatus of claim 51,wherein the instructions, when executed, further cause the MeNB to:process an addition request acknowledgement received from the SeNB inresponse to the addition request.
 56. The apparatus of claim 55, whereinthe addition request acknowledgement includes a list of admitted E-RABs.57. The apparatus of claim 51, wherein the communication circuitry isfurther to: generate an RRC connection reconfiguration message toinclude small cell information to facilitate establishment of aconnection with the SeNB; and cause the RRC connection reconfigurationmessage to be transmitted to the UE.